Telkom keeps charging me for calls to landline Numbers -

Telkom keeps charging me for landline calls whilst I have an unlimited plan i.e. for calls to Telkom numbers. They have been doing this for past 6 months - I have logged the dispute with them - they check my numbers dialled are indeed Telkom landline numbers, they say they will debit me - of which they do . . . Then they again charge me the very next month . . Why? Why? . . Service is terrible