Paid account not reflecting

I'm so upset with this company. I paid my account on the 25/11 at a vodashop. Vodacom calls me to tell that they haven't received the till slip from shop and I'm owing. I tried emailing a copy of my till slip. With no assistance. I can't believe vodacom can't help to resolve this matter. Do they want me to pay again. They making it seem its my problem