Won’t give my money back

Cancelled my insurance because my car was sold now I have to call multiple times and email to request a refund on the month’s cover money. They also say I have to provide proof my car was sold I sent the documents and they still haven’t refunded me.

Why should I proof my car was sold ? Why haven’t you refunded me when you sent me a letter saying cover was no longer valid since I cancelled? Who did you have the contract with me or the bank or the people who bought the car for me?

These are questions I am asking myself as I still wait for my refund.