Debited after settling

Hi, I took a contract with CellC the agreement was to pay R 129.00 per Month for 24 Month, end of the first month R984.57 so i decided to settle it as i was not prepared to pay so much, i Called the accounts department asking for a settlement fee with decembers fee i was given R 3620.00 which i paid on the 28 of Dec 2015 at 11:45 am , called in the number was closed immediately , now they have debited R 909.92 that I am reversing the Highveld malled called in for me and they said i was told a wrong amount that is non of my fault they just should stop taking money from my account , wont ever advise anyone to take a Contract from them. The Bank charges i want too i will email proof of payment if neccesary. My nearest Branch is highveld mall very nice people who understsand but cant refund me