MIX Telematics are ******** clients

On the 18th May 2021 i sold the car.. It turns out that the car had a tracker where it was deducting R99, 87 per month. Account number : 645415 :ContractID:***5. On the 14th June they received a cancellation request in order to terminate the contract. To our surprise on the 27th July I received an email demanding a settlement amount of R700 and if i do not pay the settlement amount the contract will not be canceled it will remain in force, they will continue to provide the contractual service and debit my account accordingly. I never signed up anything with these people and I was not even aware of a tracking device in that car because I never received any call making me aware of this issue. I do not understand all this pleas Hello peter help me.