CELL C is an unacceptable service provider

I had an account with Cell C for many years. After we moved to an area with no service Cell C just said sorry there is nothing they can do about it. After many weeks of fighting, they agreed to cancel my contracts without a cancelation fee of any sort. We took back the handsets and thought everything is settle. Only to find out that they billed the remainder of the cancelation fee. I am struggling to get a hold of them to sort this out. Its been more than a year with this problem.