Hitachi - AC not cooling

I purchased a 2 Ton Split AC from Hitachi in end of April. In a few weeks , it stopped cooling properly. I registered a complaint and the technician came and said that it would need gas refilling and we should make another complaint. I registered complaint no 12060202823 on 2nd June. Since then I have also registered a complaint on their website 3 times. Every time I call their call center, I am told that they cannot commit when the complaint will be addressed. Finally I asked them to give me the number of the Service Center in Okhla, Delhi where the complaint has been sent to - 011 - 32220014/93.

I'd be happy to know if any one can ever get through to these numbers... I have not been able to. Even if it busy a few seconds ago, no one will ever pick up the call.