Cell C just not capable

So I had two contracts with cell c, one expired, and I then opted to cancel the contract. So when it became time to pay the remaining contract I mistakenly used the canceled ones reference, twice in a row without realizing it. Once I became aware of the problem I sent all the details to cellc to numerous mail addresses to try and resolve the issue. I phoned them 3 or 4 times as well. Now the phone is blocked and I am receiving phone calls about my account being in arrears. It seems no one can or want to resolve the issue. i am at my whits end and don't know what to do further. Is their someone at cellc capable to resolve the issue??