Toyota — Faulty car with bad service

Dear Sir,unfortunately Im a owner of innova diesel. I had purchased it on 18/08/2007 first 40,000 kms was very nice to drive the car after that it started giving me trouble.There was an abnormal sound from the Engine and the car used to stop at any place without any reason despite of regular complaints to the dealer M/S Topsel Toyota Kolkata nothing was done.
It was very bad expereance . When the car reached 70000 kms it became impossible to drive the car despite my several requests dealer did not help.My car is still under warranty period but the company says that your fuel pump has gone out of order because you have used spurious fuel.Company charged me 31000/- as the replacement charges for the pump in the warranty period.
My question to the company is was it right on there part to do so. You Japenese come to India to cheat us.My opinion its a bad co.A co.with no business ethics.