I have had countless calls and emails with Gems regarding my refund claim

I have had countless calls and emails with Gems regarding my refund claim. I had stated in my email giving them my banking details as well as the receipt from the doctors office (as it is stipulated in their website). GEMS made payment to an account I didn’t give to them in my claim and now they are refusing to pay me my money back telling me I should take it up with the bank. I am tired of doing this back and forth with Gems because I am from a traumatic experience and now they are adding on to the fuel.