Failure to refund returned goods by Bathroom Bizzaire

I bought a bathroom basin from Bathroom Bizzaire Centurion on 1 Nov 21 and returned it on 2 Nov 2021 because it was a bit small for the space. Their refund it's done through a Bank card reversal. Todate I haven't received my refund. The bank said they received an instruction for a refund but they never received the money it seems like the instruction was withdrawn. Bathroom Bizzaire is sending me proof of payment only for me to deal it. I'm not getting help from anyone now while my money it's not refunded. When I say I was to go to the shop they say they are a big company they don't cash refunds.