Urban Company — AC professional cheated by charging more than the company price

I have booked for AC Service in Urban Company on May 11th. A technician named Saif Ahmed Khan has visited my location. He checked the AC and said that the gas has to be filled and charged me 3500 rs for the gas filling. Later when i checked the Urban Company App it is mentioned 2500 rs for gas filling with warranty. He has also not included the gas filling charge in the invoice bill. He has clearly cheated me and charged me more than the company rate card. I have lost warranty and also money for the service. I request you to take action against the technician and not encourage such professionals for the service