Seriously ridiculous Accounts Dept

I received a call saying I am in arrears buy a rude person who could not even convince me of who they were. So I called them straight back and was assured by the accounts dept that I was perfectly up to date she can see the only amt due is the billing for July which was debiting the next day. She said she would escalate the person who called me to a supervisor to find out why. Now I get an email out the blue saying i owe almost R6000 which is about 2 yrs of payments yet my services are still working. The lady tested my tracker on the phone told me where my car was when it was last used. So how can I be 2 years in arrears.....