Usha — USHA Ebony Neo Gas 3 Burner Cooktop

I purchased the cooktop in August. I wasn't working fine from Day 1. I lodged a complaint with USHA and they sent the technician only after i forced him to come.
He did something and said cooktop is ok but the Gas regulator has some issue. On his words we bought a new regulator but still not working.
I have sent the email to USHA twice but no response. I have raises a complaint twice but no response
The gas stove is faulty and may cause any incident at my home