Videocon — Black patches on 32 inch led tv

I had purchased 32 inch led tv of videocon from vijay sales on the 15th of may 2015. After 8 months, small black patches were visible. Thinking that it might be dust of some picture distortion i ignored them. The same patches kept on increasing day by day. Now i have complained for resolving the same for which the representative from videocon duly visited my residence and after checking said that the unit will be service by the company for which the unit will be picked up by the company. I said ok and still waiting for the people to take the handset for repairs / replacement. After calling the helpline, the person on the call is claiming that there is no problem with the unit and the person visiting my place had given this report. Now where to go and what to do...???