Game Kenilworth payback my money

I went into a game store on the 9th of March to get a quotation for a new stove I needed. I was given the quote, banking details and email address to send proof of payment to. All this was done. After a week's I managed to go back into the store and apparently the email address I had been given was incorrect. So now I don't have the proof of payment that the bank sends to the recipient email provided upon payment. My mom made this payment for me she had sent me a screenshot and Game doesn't use screenshots as proof of payment. I've tried to get assistance by sending emails but no one responds to my emails. Why are they not reversing this money that is sitting in their bank account if they do not know what its for????? I want Game to pay back my money