A 'negative' account balance of R0.00

I recently bought a new car and wanted to add my new to my e-toll account and remove my old car that was written off in an accident. I live in Kzn so I do not really use e-toll that often. After finding it impossible to access my online account to do this manually, I wrote an email to which I received the following response: "Please be advised that in order to remove or add a vehicle to an account, the account must be firstly on positive balance. Your current balance is R0.00 and is temporally suspended due to insufficient funds" So my account is completely settled, but apparently this is not enough to remove and add a vehicle?