Getting billed for service not received

Greetings. I am struggling to stop Telkom from debiting my account after canceling my contract. i had a contract with them for data but never got good service in terms of network coverage. i was promised that the signal will be great but ever since i got the contract i never even got to use 20% of the promised data bundles. i complained many times and eventually a technician was sent who then confirmed that there was not coverage.<br> <br> i then requested cancelation of the contract in March 2015 but my account is still being debited.<br> <br> kindly help please