IN DESPAIR TRYING TO DEAL WITH CELL C

I took out a 24 month contract with Cell C on 12th October 2012. I phoned them in September 2014 and advised i would not be renewing my contract nor doing an upgrade. Despite this i had endless calls plus sms messages offering me upgrades which i refused. I phoned again in October to confirm that I was not renewing. When they continued to debit my account I went into Cell C Blue Route Mall Tokai and spoke to a consultant who reassured me that if I had not renewed my contract it would no longer be valid. Since then I have phoned a number of times to try and sort this matter out, with NO success. At the moment I am on pay as you go PLUS they are still debiting my account every month. They have phoned me 2 or 3 times and i have explained the whole story and am told someone will contact me. It does not happen. So they have now *******ly been debiting my account since October last year. i have received 2 reference nos. *** and ***. PLEASE CAN YOU HELP. Fay Howard