Contract cancelled yet bill keeps pilling up

I \had"a month-to-month mobile data contract with Telkom which I cancelled on the 27th of April 2015 at a Northgate branch where same was activated. A gentleman by the name of Themba helped me cancel this contract and advised that it will be deactivated as of 27th May 2015.<br> <br> This obviously never happened and I've been paying for a service I'm not utilising. I've been calling and escalating the issue and no one will help. on July 17th I sent an e-mail to Mildred who called back and promised to have someone call me with a case number so the issue could be resolved"