MTN add unrequested items to my account.

MTN adds unrequested items to my account (Data bundles) then charges me for them. This nonsense has been going on for a year now. It is impossible to get MTN to resolve the issue. I have tried the Oakfields shop many times, logged many queries, made many phone calls, sent many requests to the call center. I have a signed contract for a specific amount and will not pay for MTN's unapproved additions. I conclude that MTN are *******. Regards L Green