bad communication and service (netstar)

I would like to put a complaint in , we had a vehicle that was financed and in that financed purchased there were a netstar tracking unit included in the contract, we took the financed vehicle for 6 years not knowing that the netstar tracking unit expires in 3yrs and we had to renew it , so no one of netstar team even phoned us about it by asking if we want to renew or are we still happy , so needless to say we have been driving a car with out a tracking unit for 3 yrs now and only now that's when they call us to upgrade our system but not for the financed vehicle for our other vehicle so when we asked them why they only phone for the one and not the other one that's when they tell us it expired 3 years ago . so we cancelled the units from netstar and went with a other brand and they still took a full payment at the end of the month we revered that payment so now they are sending us messages by saying they might take us to the credit bureau for skipping a payment . so we will be doing the payment for them but its very bad service from there side .