They are refusing with our refund

We went to builders warehouse in Louise trichardt. The cashier made the wrong quotation and, only to find it that everything she did was wrong after we paid. So now its been 2 weeks they dont want to refund our money. We have been calling the branch and going to the branch but still they keep saying they have proced the payment bit we haven't received our refund back. Terrible service and I cant even recommend it to anyone or ever going to buy anything form that warehouse