Unauthorized debit from tracker

Good morning, my last review was about tracker their device not working..... Well they did attend to me and ended up terminating my contract with them and they told me that actually my contract had long expired with them, they told that they will send an email confirming that the contract is terminated the same day I even went to the technician the same day so that they can remove their device as it was not working anymore, surprisingly they they are busy deducting R770 in my account and I've been reversing it an now they are threatening me with lawyers and the fact that they have been deducting money in my account for the past 6 months while the device was no working its not fair can I be assisted on the matter.