Toyota — tyre studs nut cut amount charged under warranty period

Address:

560077

I brought innova crysta 8862 km run (During the incident), date of registration 02/01/2018. Vehicle registration number ka 04 mu 2102. This incident took place on 23/06/2018 when i was travelling from bihar to bangalore. During the run the rear tyre which has 5 studs which holds tyre out of which 3 studs got broken into pieces near place called gaura maksudpur, gazipur dist. When taken to the nearest service station rajendra toyota, varanasi they charged me 4550. Company gives the warranty of 3 year or 1 lakh km for the vehicle then what made them to charge the amount? What type of safety are they providing for which toyota is been known?
As the vehicle was not on high speed due to which my whole family were safe, my concern is if it was happened during the speedy condition who was answerable for the lose of whole family who were travelling in the vehicle?

I request you to ask the toyota service center to inspect the vehicle completely so that the same issue doesn't occur to any of the customer and also refund the amount collected at the service center as the vehicle is under warranty period.