Service is atrocious - pathetic

I purchased a 1.5 T Samsung Split AC around 15 months back. The A/C stopped working - not cooling and I had registered complaint with the service center. There were 4 visits till now for the same problem - problem still remains - I had paid for the service charges, a capacitor and now they say gas has leaked - I have not seen such poorly co-ordinated service center anywhere - BTW - this is in Chennai. They don't understand what you try to say and they were rude in answering questions - like - the problem can repeat like this as you are using it - What a reply !!.. I have a very very bad service from this service center..Do anyone know how to register a complaint with their HO...