Refund and signature verification

my homeloan was debited twice this month i requested for a refund 2 weeks ago ,the refund form was sent to me i sent it back signed ,i was told my signature is not the same that i must go to the nearest branch to verify my signature i went in the branch, I was told that because i don't have an account with them it will be difficult to verify because they will need a bank card number to verify ,they give me the signature card form to sign as verification i sent it back to refund department but still it was not good enough this morning um receiving another email "Sorry we we cant process you refund "as the signature its incorrect.... what are telling if the branch cant verify my signature just because i dont have an account ...what must i do i need that refund back plss good ppl why do i have to suffer for my money