WesBank refund painful process

I paid off my vehicle according to the settlement quotation provided WesBank then tried to debit a further payment which I was confused about so I made the further payment which turned out to be extra and a refund is due to me. I explained to the call center agent that it was a transfer from one acc to another so no proof of payment is available . The agent insisted that even tho they can c the extra payment I must provide proof . This is utterly ridiculous when the amount is reflecting y can’t they do the refund surely WesBank can c which account it came from . The agent tells me it could have come from anywhere and I must provide proof and my banking details. Now I am suppose to chase after WesBank for money that is owed to me .