Telkom - Mondo: Refuse to cancel product

In July of 2019 I telephonically subscribed via mondo for a telkom mobile sim-only contract comprising of ten gigabytes of all networks data. When I received the sim it was ten gigabytes of telkom mobile data. I immediately phoned to cancel the contract.

Almost a year later and I have been unsuccessful in my numerous attempts to finalise the cancellation. Every time I follow up I get told that all I must do is wait. I am paying for the product every month whilst I have never used it.

Telkom says they cannot assist me as I ordered the telkom product through mondo. I do not understand this logic.

I have exhausted all avenues to cancel this product with absolutely no success. What else can I do???