Cell C suspends my service unilaterally.

Last Wednesday I had to work from home. My ADSL failed and I had to use my phone's data to connect to my office. I got an SMS from Cell C later that my service was suspended due to excessive use. When I called Cell C I was told I had to pay R1300 for my service to be restored. I have been on a contract with them circa 2002. I renewed my wife's contract with them two weeks ago. I am going to port both our numbers to a different service provider and they can try to sue me. I want them to pick up the new phone and cancel the new contract. I need my phone for my work as I do after hours support for FNB.