Wrong debit from my account for more than a year

Last year someone from Netstar phoned me and said that after three years of paying for my tracking device it has been paid and I will only pay for the tracking, not the device itself. I have unfortunately still been deducted the same amount every month since December last year. As per my conversation with the gentleman the payment would actually decrease, which of course did not happen. Can someone please contact me to rectify this problem and return the premiums paid.