Incorrect Billing

Tracker is billing me more than I what I agreed to when I took out the contract. I called on the 27th of July 2015, the call was retrieved and it was confirmed that the sales consultant loaded the incorrect package on both vehicles. I was informed that the query was sent to the sales consultant and his manager to rectify this and contact me once done. I followed up on the 4th of August 2015 but have not received any feedback yet which is a clear indication of how poor Tracker's customer service is. The fact that Tracker's terms and conditions states that they will not be held liable for incorrect billing and only refund clients for up to 12 months of overcharging them, once the client can prove that they were billed incorrectly, creates the impression that they not only condone incorrect billing but that it occurs so often that they would rather cover themselves as opposed to putting preventative measures in place to avoid it from occurring/ re-occurring. Cancelling the contract will result in a cancellation fee for both vehicles so what recourse is there to have this rectified considering that it's almost two weeks now with no guarantee that I will not be overcharged going forward