Was this a case of separation anxiety or boredom?  Or both?  The vet asked for more details. These were as follows:

History. 
The puppy was hand-raised by a professional dog breeder and sold to a pet shop.  It was not an orphan or had multiple owners.  It was not acquired from a shelter or pound.  Therefore, its past environment was stable as it did not have many changes of owners. 

Behaviour.
The puppy whined when confined to the play pen. It was given the freedom to roam around the whole apartment.  It  refused to urinate or pee on the newspapers only when the owner was away.  

Many owners would associate this with retaliation. The puppy was doing this unsociable act on purpose.  

It followed the owner around, whine excessively, urinate and defaecate "purposely" on tiled floor instead of newspapers when the owner was not around. It destroyed property like chewing its playpen, newspapers and furniture.

Based on the above observations, this was most likely a case of separation anxiety. 

Solution.

The dog trainer provided a solution known as crate training. His fees of $300 were considered money's worth.  For the past few days, the puppy was quiet and did not " mess up" the whole apartment. So this method was working effectively as far as the owners were concerned. 

CRATE TRAINING 

A crate is an enclosed "cage" with a door.   
Crate training is an alternative way of toilet-training (house-training or house-breaking) a  puppy. 

Basically, the puppy is kept in a crate for 1-2 hours. The puppy is taken out by the a person, for example, the domestic worker to urinate and pass stools on the newspapers in the exercise pen or confined area.  After that, it is put back inside the crate for 1-4 hours depending on its age. 

Most 8-16-week-old puppies will not dirty its crate when confined for short hours. They will wait to get out to pass water or stools. 

In Mrs Wong's puppy, the trainer recommended that its feeding time be fixed at 8 a.m and 5 p.m, not at  8 a.m and 8 p.m.  The early evening meal would allow the puppy to do its business before everybody retires to sleep.  Puppies usually pass stools within an hour of eating.  With-holding water after 8 p.m will help the puppy to control its bladder. 

Once the puppy is given a routine, it becomes toilet-trained on the newspapers via the crate training method.

Crate training is more effective for over 12-week-old puppies as they have some control over their bowel and bladder.  Such puppies pass stools around four times a day but pass urine more frequently.    

However, a person must be present to take the puppy out regularly in less than 1-4 hours to make this method effective. 

Being caged up in a crate may sound "cruel", but it is one effective way to toilet-train a puppy that cannot be trained by other methods. 

CRATE TRAINING TIPS  

Wild dogs seek cave-like areas to sleep or rest and will keep them clean. The domestic dog seeks similar areas like under the table or bed. A crate is a substitute for the domestic dog. Crate training tips are as follows:

1.  The crate size allows your dog to stand up, turn around and lie down comfortably. It is not so large that the dog has room to relieve himself away from the sleeping or lying down area.

2.  The puppy should be crated up to the maximum of 4 hours at any one time.  Generally, 2-, 3-, 4-month old should be crated for 2, 3, 4 hours at any one time.

3.  Most puppies over 3 months old can be crated all night. As dogs are pack animals, put the crate in your bedroom at night so the puppy can sleep more peacefully.

Most owners put the puppy in the kitchen and complain about whining. Ignore the whining  on the first night home if you can't put the puppy in your bedroom. Some owners put the crate inside the master bedroom bathroom which has the floor lined with newspapers.

4. Wake up in the early hours of the money to bring the puppy to the approved newspaper potting area if he wants to go to the toilet.  Doing this will speed house-training.

5. After the early-morning toilet visit, put the puppy back into his crate with a food-stuffed rubber toy or chew bone so that you can catch up with your sleep.

6.  Opaque plastic crates are preferred by puppies as they feel safe. If you have wire crate, use cloth to cover the sides and back, leaving the front uncovered for air to flow in.

7. If nobody is at home during the daytime, confine the puppy in an exercise pen, puppy-proofed room or securely fenced yard or garden away from sunlight. Do not crate the puppy as it needs space to exercise and relieve itself.

CANINE SEPARATION ANXIETY  

A dog feels very depressed and anxious when left alone. Its behaves by showing the following: Destruction of the owner’s property, attempts to escape and other behavior that may be injurious to the dog or annoying to people sharing the dog’s environment.  

Separation anxiety is a disorder of behavior. It occurs only in the owner’s absence. The owner may feel that the dog wants to “get even” with his owners for leaving him.  However the dog feels anxious being alone.

It is difficult for most owners to ignore the whining of puppies being confined in the play pen.  Mothers are usually the ones who feel sorry for the little puppy and let it free to run around the apartment. 

The noisy puppy confined alone at night may also irritate the neighbours or family members. 
Putting the puppy in the play pen inside the bedroom at night may be a solution but it may not be practical. This makes effective toilet-training difficult.

A play pen or exercise pen consists of 4 or more separate pieces of fences which can  be linked together to enclose the puppy.  It is not a crate as it has too much space for the puppy to relieve itself. Newspapers can be placed on the floor to start paper training.  An external water bottle permits the puppy to drink when left outside to play. Newspapers with urine smell should be placed outside the crate to aid in toilet-training.

Once the puppy knows that it gets attention or freedom for whining or barking, it persists in behaving badly to get attention.  Chewing property is a common behaviour of puppies. There are anti-chew sprays for the protection of furniture but these may not be effective. 

Toilet-training by confinement in a small space such as the play pen is successful if no attention is given to the puppy for the first 14 days at the new home.  Most owners report success within 14 days if they do not pay attention to the puppy's whines to be let out of the play-pen unless the owner wishes to take it out to play with it.