Getting Billed for calls made on a sim card that is not in a device

Telkom is insisting on billing me for calls i am not making on the sim card they allocated to me for my landline. This has been happening for almost 6 months and i keep asking them to reverse this. They have done it twice and now refuse to do so and instead are telling me to upgrade my contract to cover calls. However, I have not had my sim card in the telkom router they allocated to me since September 2020 and yet I have invoices for phone calls.

Can someone from Telkom kindly sort this out, because this makes no sense.