Telkom is shocking

subscription doubled last 7 or 8 couple months. Called Telkom, not much help. Then went to branch, cant help, no call back recd as dialled from branch. Contract should have ended in may, then told june, then july. Finally cancelled telephonically but last pmt end july. now i receive a Final invoice for a further premium due by 31 August. Service is pathetic and they keep ripping people off!!!