Harassment from netstar collection company

I have been harrassed by altech netstar and their collection company since last year..my car was written off in august 2017 and i called in September immediately after being discharged..I reguested cancellation of my tracker countless times and tge only reply i got was "ok" but nothing ever happened. I also send emails to cancel but they were never attended.They only stopped deducting money for teo months and continued with unauthorised debit orders other months when i was not aware.

Now i keep getting calls from hybrid something from a lady that literally forces me to give her my banking details for 200 that i miraculously owe. I will never use altech netstar again and regret ever recommending it to my friends and family..