Worse services provider with ridiculous billing

I have a month to month contract with Telkom of R499 account number *** to my surprise my account has gone up from R499-R6000 monthly . I have visited the branch on numerous occasions with a hope of trying to get logic of What was happening and each time I was told that they had a billing problem with the system from their head office and I was promised that the error will fixed. On the 1st of July my account was closet with no explanation or what so ever and this happened just after another visit to their branch.