Paying for Tracker of car you don't own anymore

with all the tracking companies netstar has a bad service that i have seen, my car was in accident and it was a write off, i called during may to cancel the contract i was told the was 1450.00 i had to pay to cancel and my contract was ending end July. i reversed amount for 3months . Someone from the finance called me in June and i told them that please cancel my contract as i don't own a vehicle anymore he said and he told me to pay 1600 and i told them i don't have the money he said at least pay R370.89 end of June that was done., i cant pay for car i don't own anymore can they cancel. it was not cancelled till this day. Now im getting call log of the vehicle which i think its been sold to someone else. On the 8th of august i got a call that im owing 1500 if im not mistaken i told them again i don't have a car, and my contract ended in July why are my still paying. end of this month they debited again after sending an email to cancel.