Less than appalling service

It is an outrage, At the end of July I accidently over paid my account with +/- R2000. I immediately tried to rectify this as it has a significant impact on my monthly budget. Ever since I am struggling to get a refund. Each and ever time I log a complaint I am requested for proof of payment and proof that the transaction was made from my banking account. This was submitted on several occasions. No feedback or response from their accounts department or from anybody as matter of fact. I logged another complaint Vox ***1, and once again received a request for a my debit details. How the continental can I make an over payment if it is a debit deduction??? As per the details it is clearly a monthly payment made via EFT!!! Trust this complaint will be clear enough for them to have the decency to respond, Telephone calls are also acceptable, seeing that when I wanted to change my email account for not receiving any statement it also became a debate.