Bad service on return equipment

In October 2017 I bought Part for my Opel Corsa at Imperial GM in Vereeniging , when I started to work on the vehicle in Dec 2017 I realized that the parts ( Pipes ) didn't fit on the car and I took it back to them but they refused to refund my money.

Even when I explained the reason to them why it took me so long to returned the parts to them.