I bought roofing material from Midrand Hyper Hardware

I bought roofing material from Midrand Hyper Hardware. Upon communication with them I was specific on the type of roofing sheets I wanted. Got quoted and paid. Roofing sheets were delivered, however wrong roofing sheets were delivered to me. I was only made aware of this after the roofing was installed. I contacted them they said dispatch sent me the wrong roofing. I have asked for a refund in price difference and I still have not received it. I have proof of how the price kept on changing during the process of me having to get a quote.