Hitachi / AC
No respance for complaint

I purchased one 1.5 t ac in the year 2009 and the AC stopped work about 10 days back. A made a complaint through phone to their centalised service call center and the service man visited after 2 days declared that the AC will be picked next day for rectification at Patparganj service center. That was the last thing happened after that no action but just false assurance. Lot of repeated complaints by phone and emails made without any result. None of the emails were answered. Their phone numbers at central service center often goes disconnected during conversation. The phone numbers at service center are either busy or not attended. I do not know what to do know. Can anybody help me