First I would suggest you try and find a friendly independent garage for future problems. Dealers often throw new parts at problems till its fixed (at your expense).
I doubt if the fault code is any way related to the transmission.
P2102 is “Throttle actuator control motor circuit low” this could be a fault in the throttle body it could also be a poor connector or wiring.
It would be prudent to clean the throttle body, I did mine at 50,000 miles and there was significant carbon build up.As throttle bodies get older they get gummed up with carbon, combine this with damp and cold weather and things stick !!
Cleaning the throttle body should be reasonably cheap at an independent garage.
(Say maybe an hours labour ?)
Alternatively don’t rule out buying second hand parts for older cars, obviously a dealer would not want to fit it !!
If you know the part number of the throttle body ebay is a good source of cheap used spares.
See (example - not sure if this is the right part)
04 05 06 Toyota Camry Throttle Body 4 Cyl | eBay