Budget Car Rentals services SUCKS

Why is it that Budget makes a mistake on an invoice by charging more than double for 1 months rental, I pointed out to them that this is not correct. They said they sent an email or communication to their bank Nedbank, now for the bank to solve the problem and give me the credit will take 7-10 WORKING DAYS. I've never heard of a more pathetic excuse and the service over the phone SUCKS AT BUDGET!!!!!