Change of Ownership

Good day, There was a change of ownership against the tracker I installed on a vehicle I have since sold. This change of ownership was done in October 2018, but to date I am still getting monthly debit order deductions from Netstar. I called to inquire and they could not explain why I was still receiving debit orders post the change of ownership. I would like to request that I please be reimbursed for all debit orders post the change in ownership, and that any future deductions be stopped with immediate effect, else I will resort to legal assistance. My ID number is ********** 744089.