Frustrated & annoyed

I took out a data contract which i canceled immediately as i was unhappy with the deal. The modem and sim was collected from me however I am still being billed for a sim and router that I do not have in my possession. I have logged a query with Telkom in Jan even though i requested cancellation in Oct/Nov 2019 ref no. ***3. I have called the call center and was advised on numerous occasions that it will be escalated to a manager still no feedback.