Cartrack horrible service and threatening customers for no reason

I recently had the tracking unit in my old car removed after buying a new car. Cartrack never cam back to me to schedule the re-installation of the tracker unit in my new car. Only today got hold to schedule it. And today I receive a threatening email that somehow I did not pay my account and that you will not honor the terms and conditions of the contract. This is complete bull****. The new units have not even been installed yet and by monthly debit order did go off like always. The cost of installation I said I will do by EFT. But the installation did not even happen yet because of your useless staff. And I never even received details of the amount to be paid and to which banking details. Sort your **** out or I will cancel my contract with cartrack