Eft reverse

I used the self service option on Volkswagen financials services phone system to get my settlement on my account. The settlement was sent, I paid the amount with references they supp**** on the letter. When I phoned on the day the letter was supposed to have expired about why the amount hasn't been allocated to my account. I was told that the reference I used was wrong and that I must go the bank and have the EFT reversed and repay with correct reference. With tears in my eyes I ask you how do you reverse an EFT? It is not possible but two people from VWFS told me to do so. Finally I got hold of someone from Wesbank who underwrites them and they explained to me what to do, the problem is still to be fixed but at least they didn't tell me to have an EFT reversed. I don't understand how uneducated people can work for a financial institution and be giving such bad advise. Not only was the letter from them wrong but they give out impossible advice.