Bad service and mistakes that get customer listed on ITC

Cell C requested to upgrade my contract but instead a new line was opened. I then canceled the new line but they took over 3 months to come and pickup the device. The contract was finally cancelled but now the account still has outstanding amount which was not cleared. I have logged 3 cases to clear my account with no success. Now Cell C handed over my account to legal which the affect my credit status. My life has now stopped because of the mistake from Cell C which they fail to correct. I have been with Cell C for over 4 years but after this whole issue. I have since cut ties with the company. Very disappointing situation that I had to deal with.