Refund only part of what was agreed

It took more that 3 months for Cell C to sort out the problem that they charge me wrongfully from August 2014. Then they only agree to refund me from February 2015 to June 2015. This amount to R4 730.79, they agree to pay this, but then only refund me with R3 923.85. This is R 806.94 sort. <br> Then there is also another R1 634.41 that they deduct from my account from August 2014 to January 2015, that I still need them to agree and refund me. It does not help to phone their help desk as you get send from one person to another. I am so fed-up with them!!! This is now the 3rd time I have to go to this site!