Wesbank- pathetic customer service

I am having SO much trouble with wesbank. I had vechicle finance with them, and settled my account. I transferred way too much money. I send numerous emails, without any assistance. They seem useless, as they keep asking me for proof of payment, which I explained to them- I transferred the money from my FNB account and did NOT make a payment. Therefore I can not get a pdf proof of payment. How do one go about getting your money back...