Unable to cancel (a completed) Vodacom contract

I have been a Vodacom client since 2003. I purchased a tablet with a separate contract (MyGig 2 TopUp promo) in 2018. Early last year (2020) my tablet was ******. The term of my contract ended in August 2020. I informed Vodacom that I do not wish to continue with this contract, in view thereof that I no longer have the tablet. I continued receiving calls from Vodacom offering to upgrade the very same contract. In spite of repeating that I have requested the contract to be cancelled (I have kept 5 sms responses from Vodacom indicating they are in the process to cancel such), and in spite of doing 3 walk-ins (drive-ins - I am wheelchair bound and it is a tremendous effort to organise transport) to Vodacom shops for assistance, up until this day I find that the ***** not only has my tablet, but I am paying for his monthly data!