Take a lot and poor quality products

Bought a laptop bag in February. The following month in March the laptop bag was torn on the belt. I logged a return they exchange it with the new one. After 2 months same thing happened to that bag I logged a return and asked to be credited into my account they declined and returned the same bag which is torn?? Why didn't they give me new one since they are unable to refund me?? We pay a lot of money for poor quality product. That time I also had to follow up with them on the delivery??? My reference number for this case is ***4