Incorrect acount for last 4 months

I only have a landline which I used for internet. Nothing else. For the last 4 months every month my amount keep increasing. I also didn't receive any invoices for the last 3 months. Telkom just keep deducting more money every month without even sending me an invoice. When I contact them they refuse to help me an just pass me on to another department. I have logged more that 6 escalations for this problem on there website. Still nothing. No responds. Nothing. But it you don't pay they contact you within a day. Telkom is the worst service provider ever.