[Resolved]  Sunflame/ Double Gas Burner — No service after repeated complaints

I had purchased a Sunflame Gas Burner in August 2009 from Sarojini Nagar Delhi. The burners were leaking gas and one of the burner knobs were defective from the begining, the other burner makes noise when on. After I lodged the first complaint, a technician came and replaced the knob, he said that the gas was leaking because of the knob. From the very next day onwards, the problem started again. Flames come from below the burners, make hissing sounds and gas smell fills the kitchen. On complaining again, even after 4 days no technician has turned up and the company says, the field guys will visit shortly.
Is this how a dangerous situation should be treated?, because of lack of options my wife has to continue using the stove. I demand an apology and total replacement of the stove as it is still under warranty. Please help.