Update ITC

I had a contract with cell c from 2***, there after the number was deactivated. On ITC it still reflects that I am paying for this contract even though I no longer have an account with Cell C. I just called their call centre now to ask them to update my record on ITC - the agent that I spoke to did not understand what I wanted, I was on the call for 18 minutes and I had been requesting to speak to a supervisor - he ended up cutting the call.