Tata Motors — Concorde Motors trying to thug

Address:

Mumbai City, Maharashtra

I own a Tata manza (mh 02 ch 515) My car is with Concorde motors worli for an issue with glow plug / heater coil. The car is insured comprehensively and is covered under extended warranty as well. The service executive says that in order to replace the glow plug the engine head has to be removed and replaced which will cost 20000 extra. When spoken to the senior she has nothing to say apart from sorry and nothing is in our hands and we are helpless. When asked for an explanation in writing the senior says it will take one day which shows something is not right. My query is not being resolved. I would like someone to look into this matter and help me from being cheated.