Hash 28 make sense i mean i got few rates and they are.
New standard pistons, 2800 Japanese
New Complete seals and jans kit genuine 4100, japanese 2700, Chinese 1100
Pressure plate and clutch plate, 4500
Clutch bearing around 1400
timing bearings will be arouind 1700
Vavles were around 2700
Water pump if i rem wil be around 2500, GMB Japanese
Oil Pump will be also around 2500,
Mechanic takes around 3500 and Kharad guy will take around 3 for new bores and all.
Plus oil change
So add all this up and it will touch 28k, The thinking is if your going for a overhaul than everthing will be changed to new one so the car can be trouble free for 4 to 5 years.
I trust what my mchanic do i mean he is just like me perfectionist he will not be satisfied with some thing less :p. And he knows if there is a small prob i wont ignore it and come back to him so
BTW i was not having any prob on cng average which was close to 160 KM Local with 55 KG and now i feel its improved i will confirm this.