Horrible company that just wants money

I have a contract for a set amount. This is what I signed and arranged with the car dealership. I was told they fixing this but I have received an invoice for the wrong amount. I am livid. Tried of asking for help to fix this and then nothing happens but they will call nonstop when you reverse the debit order. I don’t trust this company. I ask to speak to a manager and no one knows one, I ask to see my contract that they have as they state that I have agreed to their amount (I have agreed to a different amount), I ask for contact to be via email and I’m ignored, I ask for help I’m ignored. I will not change this review until this is sorted. I want to cancel my contract regret going with Cartrack so much. Worse than Home Affairs.