Wrong billing

Worse service provider you can take contract with , I have a SIM card contract with Telkom that is placed on a router from May 2025 I have been paying more that then stipulated/agreed amount I logged a call last month they promised to pay back the amount and that I wouldn’t be paying double the amount they charged me that month . Come month end I payed double and they sent an invoice that I owe them triple the amount. They claim that it’s an once off subscription from my other contract when I tell them I have one contract with them and it’s SIM card that is on the router there’s no traces that SIM card it’s being used recklessly and mind you this is a unlimited data SIM card.