ok, so i work at bestbuy and i have never heard of need a "key". theres two things that i can think of. one when they say your car is too new what im thinking is that you had a guy in a blue shirt try to set up an appointment for you. what you need to do is talk to the installer himself. if you talked to someone in blue and they tried to setup an appointment you will get a message that says "sorry but your car is way too cool for us please see you local installer to make an appointment!" (lame but whatever). as far as needing a "key" we need both of your keys to be able to program the new remote for your stang. thats the only "key" they would be talking about. so i hate to say it you are getting lied to cause i JUST had our installer do mine. no extra harnesses or anything, no "key" (just the car keys), and yes when i tried to set up my own appointment i got that "your car is way too cool message" (PSSHH i know this!). if you need any other help with getting around this problem PM and let me know. whatever they are telling you is random stuff and i think its pure laziness in all honesty.