overcharge

I have a contract with Cell C for R 59 per month /24 months. <br> However all of a sudden Cell C deducts R 63.99 per months. As from Feb 2015<br> Why is Cell C breaching our contract. No communication was received beforehand or authorisation was given for this increase. To me acontract for 24 months is at a fixed prize and binding no changes can be made without each party involved permission, In this case there was not such a thing.<br> A refund for the months overcharged would be in place. This is from February 2015<br> Please rectify on your system that the following month deductions are R 59 as agreed upon. <br>