Buffalo logistics refusing refunds

Dealing with Buffalo logistics customer service is impossible. I mistakenly paid the customs tax twice due to a glitch with their system and I have now been struggling for over a month to get a refund.

Each time I email the support line, I describe the problem and submit the refund form and my bank statement as proof of the double payment. After that I either get ignored, or get told the package has already been delivered (which has nothing to do with my query), or that they can't accept a bank statement as proof. The last one is very confusing. I paid online with a credit card using a link they provide and they can't accept bank statements as proof? I keep getting asked for two proof of payments with the account number paid etc but that type of POP is only possible with EFT payments, credit card payments online only can be traced with a bank statement.

This has been extremely frustrating. I am probably never going to get my refund. Buffalo logistics will just ***** that money and I will be stuck in the endless loop of trying to explain the problem to their useless customer service.