"We reactivated your account after you paid it"

1 Year after my contract was settled and paid for they tell me they reactivated my account and now I owe them R2000. Spoke to a lady from Vodacom Collections saying that they reactivated my account after my paid up my arrears. Just 2 months ago I was in a Vodacom store to apply for a contract where they told me that I had a contract that was in "Pre Legal" for which I spent 2 hours on the phone with Vodacom with no resolution bouncing from department to department. Eventually deciding to leave the issue and save my sanity since they all told me that I owe nothing on the contract. Now I get an email saying I owe R1800 when I wasn't notified that my contract is getting reactivated.