MTN Wi-Fi Contract offered through Mondo.co.za

I was offered an MTN contract via Mondo.co.za on behalf of MTN telephonically. Mondo.co.za offered the contract for specific amount and I was billed over double the amount on the 1st month contrary to the offer of the 1st month being free and continuation of contract subject to me confirming satisfaction with the services received by the end of the 1st month.

I lodged a complaint with Mondo.co.za who investigated and confirmed that the dispute was valid, and the telephone consultant misled me. They said I would not be liable for any cancellation fees, and advised me to return the device, which I did in May at a MTN store. At the end of May I was billed and I paid the contract following legal action threats from MTN. I followed up almost daily to get Mondo.co.za to cancel this contract, and they confirmed in June that the contract was finally deactivate/closed. However I am STILL being billed by MTN. I have been making queries on both Mondo and MTN customer care email address. My account is being debited, every now and again and resulting in unfulfilled payments. MTN is threatening me through email of taking legal action against me.