Device and sim card card collected but the contract is still open and no explanation.

In August I was offered a deal by Mondo but they only delivered it on the 21 September and was activated 25 by 27 it was out of data and when I called they said the packages changes from time to time from Telkom that is why my subscription was lower and paying more than I agreed on and I decided to cancel the contract because to me that was *****, on the 2nd October by the 3rd October they sent someone to collect their property which I last used on the 26 Sept because on the 28th the data was already depleted, but still today the contract is still active not cancelled I called for answers no one have them, they collected their device sold to someone else and I will be paying for it because my debit date is 25/10/2018 and I don't even have a clue what will I be paying for, the data I used in September or my normal contract, I'm so frustrated I regret the day I answered their call because I will be not in this mess now. Please people don't respond to strange calls offering bogus deals if you want something go to cellular shops you will get what you signed for.