Bad client service

We are having problem with multi choice. I was using EFT payment to pay them. So since it's festive season, I Decided to create a stop order which went through but I was disconnected and this is not happening for the first time. The only thing that can proof I have paid is my bank statement but at lebowakgomo multichoice they said it's not accepted. It doesn't make any sense at all bcz it is the only proof there is for a stop order payment. I'm really not happy I'm taken to and fro