What contract?

A few months ago started seeing my acc being debited by matrix all of a sudden eventhough i have been with cartrack ever since i got my vehicle. So i reversed the debit orders that i could, thinking they woud call me and ind out whats going on. After months no call, only trying to take up to 2 payments per month now and letters from their lawyers saying i must pay arrears before they hand me over. Called them eventuallly myself asking for proof that i have a contractual aagreement with them. 4weeks later no proof, er the debit oders and letters from lawyers keep coming. Very bad