Re: SCM Problem
First, welcome to the forum. Are you getting any DTC's that will give you a clue what all is going on? If you're having trouble with the key fob, alarm, etc. the stealer could be talking about the Sentry Key Remote Entry Module (SKREEM), also known as the Wireless Control Module (WCM). If this module is defective it must be replaced, as there is way to repair it. Unfortunately, if it is bad, you'll have to go to the stealer since it will need to be programmed with your key(s) ID No's., TPMS Sensor ID's, and the "Secret Key Code" to name a few. One caution for you to be aware of is that if the stealer can't recover the Secret Key Code, you'll have to purchase all new keys. Bottom line is to hope they have done this before and know what they're doing.
If they're talking about problems with the clockspring, then they're talking about the Steering Control Module (SCM). This is why reading any codes is important. The horn switch is just one of the items that interfaces with the clockspring and SCM. Are any other of the rotating items on the steering wheel (radio controls, cruise control, airbag control, etc.) giving you a problem or throwing a code or showing a light? This job can be done by someone that is highly proficient in mechanics/electronics but, since the airbag is involved, I know I wouldn't want to mess with it. Accidently blow the airbag and you'll be out another $2000 or more.
I am not sure what they're talking about with the "TCM", unless you're also having transmission issues. The TCM is the Transmission Control Module and it, along with the PCM controls all transmission actions. Are all upshift/downshifts and shift qualities (both light and wide open throttle) working properly?
Like Madanio24 said, get a second and maybe a third opinion before you jump into this one. If the second and third opinions come out the same, as much as I hate to say it, I'd take it to the stealer, after I quizzed them on their level of expertise with R and R'ing these items. The price (including parts) really doesn't sound out of line for those jobs.
Good luck, and let us know how this all comes out.
05 LX/RT & 06 WK/GCO, modded similarly, MDS "ON" Light, Vortex Gens, Debadged, DashHawk, BT Catch Can, SRT CAI W/Add Air Inlet, K&N Filter, Sonnax Trans Press Booster, SC Tuner W/Adv Trans Tuning App, DS Tuner, Cust tube headers w/3 in. catback, Bilsteins, SRT frt/rear bumpers, Eibach SRT Lwr Sprgs & Sways, FRI Sidewinder Cam Adv 2*, 6.1 valvetrain, SLP 25% UD Pulley, BBK 90mm TB, SOS Coils/.060 plug gaps. 20 in. SRT Reps.