Sagar Tata Motors - Extreme fraud by car dealer

My car Tiago XT *rd service was due in the first week of August. So I went to Sagar Motors, G.Noida branch for the car servicing on *rd August ****. Initially, they give the estimated bill of Rupee **** in the Job Card, tentative costing of each thing are below mentioned in their Job card
*. Engine Oil = ****
*. Oil filter = ***
*. Car lubrication =***
*. Brake Pad cleaning =***
*. Wheel balancing =****
*. Wheel Alignment =***
Then they insisted me to buy one time AMC of Rs ****. So this way I could save Rs **** (Rs ****- Rs ****). As a customer, I agreed and bought the AMC. At the time of delivery, they denied to provide me with the final invoice and AMC bill, said they were having some system issue and they asked my email address so they will send me an email next day.
After so many reminders I got the final invoice on my email. Final service invoice had only a few things of cost Rs **** only, that given below
*. Engine Oil = ****.**
*. Oil filter = ***.**
*. Wheel balancing = ***
*. Wheel Alignment = ***
Means they have performed only these things in the car. Again I went to the Sagar Motors service station and ask the question if the final bill was only ****, so why they insisted me to buy AMC of Rs ****. Their manager said, we have performed all things in your vehicle that we have written in the Job card cost of ****. By this way, you are in the profit but don't have any bill that will show Rs **** work. They understand their scam and finally said sorry only.
My complaint :
*. If you have done the work of **** provide me with the bill shows that amount.
*. If really my bill amount was only ****, so why they insisted me to buy the AMC of **** before servicing.
I raised this complaint in the TATA MOTORS complaint desk also. From last ** days they ask me to wait, again and again, they were forwarded this matter to the dealer office but I didn't get any resolution of this matter till now. Pathetic customer service from the tata motors.
I am really demotivated. Please help me out.