URGENT : Cancellation of Fixed line

Shocking Service - I have attempted from mid-January 2018 to cancel my Telkom fixed line due to moving house end January 2018. I sent in a cancellation mid-January, again end January and 5 times since as well as more than 10 phone calls to their call centre. I have seen a recent bill and they have continued to charge me the monthly fee plus interest charges. I need this service cut from 31 January 2018 and the account rectified urgently.