Furious

My wifi service is with Telkom. Month to month billing. I ran into arrears for 2 months due to unemployment and my service has been suspended. Started working again so I called Telkom to check my balance. Only to find that they have been billing me monthly. Have a case number and consultant said someone will call me back. 6 days later and no call back. I dont have a contract with them. Clearly stated month to month billing. Why am I being billed for months for services I didnt have. Please assist