Cancelled contract still being billed

On the 11 November 2015 i went into canal walk autopage to cancel my contract with autopage, one month beforw it ended, as they instructed me to do. I wrote a letter by hand, submitted it to the consultant and he drew uo the rest of the paperwork and made me sign it. He said that my contract is no cancelled and will end 12 december. Then i will be put onto prepaid. At the end of december, january and February i still received bills for the contract. I had received an sms on the 12 th of january starting that i am now prepaid. When i phoned the customer service number the first time they said that it will take a month to process the cancellation after the 12th of december. No one informed me about this at any stage before this. Upon receiving my bill at the end of february i phoned the customer care line. I spoke to patlako on the 2nd, aaron on the 9th and lenard on the 17th. No one had a straight answer for me.. except for how rude the female shop consultants are.in canal walk. I am so dissapointed that this had to end like this. I have one more contract with autopage and would gladly pay a fine to stop it as autopage is the worst cellular company i have ever met.