Keep taking my money on debit order

Netstar Installed tracking devices in my Vehicles in 2007 and 2011, last year I wanted to test the units to only find that they are obsolete. When I wanted to terminate the"non existing service" my case was referred to retention department, I am still waiting for them to get in touch, in the meantime I have contracted with another tracking company. Netstar is still taking my money on debit order every month, even though I asked that it be terminated. Case: CAS-***-G7Y8