Apple India — Discrepancy in Apple Service Center

I had submitted my laptop to Apple Service Center in Kolkata for repair. However, the service was very dubious. They charged me around Rs. 50, 000 for repair stating that they would change the screen, however when repaired service center said that the screen was fine, they have repaired the board and battery and the charge is the same. There were not even giving me a bill. However when I demanded they gave me a bill that did not look original. The service center is in City Centre 1 in Salt Lake City, Kolkata, West Bengal.