Tata Motors — Excessive labour charge for service.

Address: URS kar TATA motors, Mysuru, Karnataka

I gave my nano for 5th service and the bill amount is 8, 800₹. Out of which 4, 500₹ was labour charge. Can anyone justify this to me? The total service cost is supposed to be around 3, 000 - 3, 500₹.
They sent a message of estimate cost of 4, 500₹ But gave final bill of 8, 800₹.
This is pathetic. We trust Tata motors and give our cars for service in showroom always but the service team and Tata motors employees charge us however they want. Few months ago I gave my nexon for service and it costed 7, 000₹. How can nano service cost 8, 800?
We feel cheated. Please look into this ASAP.