Trying to get dealer to lower price on remote starter opinion

[geepondy]

I bought my 08 Fit basic in July of this year. At the time the business manager gave me the hard sell on a Prestige brand keyless entry/alarm/remote starter package. When I said I would stick with the keyless entry alarm system for now and consider the remote starter later, he said ok and we completed the deal. The literature that came with it says the remote starter is an option and the keyfob even has an extra button designed for the remote starter. I called up the Honda service department today to enquire about the cost of the remote starter upgrade. He stated it wasn't just a simple upgrade but used an entirely different module and he essentially would have to replace the whole system. He quoted me a price of $500 and said this was even a discounted price. I later called an independent auto security place and they basically agreed with what the service manager told me.

I then called the dealer business manager who sold me the system and told him at the time I declined the remote starter part of the package but expressed an interest in possibly accepting it for the future, I should have been told that if I did not have it installed at this time, it wasn't a simple upgrade but rather a complete different, expensive package. Had I known that information I probably would have then had it installed at that time. I got the impression, he didn't realize that either but he would see if he could get me a lower price. This was early afternoon and I never received a call back so I think he may have blown me off. I'm considering writing the dealership owner a certified letter and explaining my situation and see if he'll lower the price. Do you think I have a leg to stand on or should I go about this a different way? The independent security place I called said he would replace it with a different system that included the remote starter for $450, but I forget the brand of the system he quoted.