CELL C SUCKS

BAD BAD SERVICE!!!!! I have had a CELL C contract for 4 years. After cancelling it in March, I have not heard - nor received any correspondence from them. However, today 14 June I received a call from debt collectors regarding my CELL C account. Stating that I owe R 2216.89. After calling them for almost an hour - speaking to 5 different people, I have not yet spoken to someone who can help. Every time I call the aske my security questions - one time all is in order - next time I fail the questions..Yet, all my details are the same, again, and again and again. I will not leave it like this, I will not be held responsible for the amount charged. I need a cancellation letter from them to send to the debt collector, but therefore I need to speak to the retention department - where I also failed my security questions??? CELL C SUCKS!!!!!!!!!!!!!