i might be wrong about the plugs change stuff but i dont really agree with ur "3S dealer only" policy.infact my own experience with 3s dealers has been toooo bad... u can find that in my earlier posts... the supervisors there advice people according to the user manual (which is not usually applicable because of the bad fuel/cng installed in the cars)
there is absolutely no need to change the brake oil fluid at 40,000kms while changing the transmission oil at that mileage is absolutely necessary.
as for mechanics, i ve found out that some of the open market mechanics are better then 3S dealers mechanics! my own car was maintained by honda 3s for 1 lakh kms, everytime i stepped into their facility, i walked out with a new issue until finally i stopped going there n visited a local mechanic who had good reputation.i can safely say, infact i can challange that hes the best person for all the new cars in my area.u can bring in any car, accord, camry prado LC or any other, he ll be able to fix it with any issues.
Dont just follow other n visit the 3S dealers JUST because they are 3S... kindly use ur observation, see if they really know the car better then ur road side mechanic, otherwise paying 7 times more then desi mechanic wont get u anywhere...!!! hope u get my point!