Refusal to give banking letter - Premium service when it suits FNB

I have a refund due to me from a supplier, and according to legislation it needs to be refunded into the same account. I need to get a bank letter to say that either the account belongs to me or is linked to another account that I have a bank letter for. Or I can provide the supplier with ALL of my credit cad details (incl. CVV). FNB agree that I shouldn't give my CVV number, but apparently don't do letters for credit cards. So they basically are forcing me to expose my account to ***** and th3ft. Also, their "Premium" Banking service that's available "24/7" is only available when they feel like helping you and their turnaround time is shocking. Can I raise an invoice to FNB for lost refunds and the interest due, due to your antiquated policies?