Sony India — utterly poor services

I bought the led model kdl43d800d in november, 2016. And recently i m facing the problem in the display which shows vertical bars.
For that i contacted the service center - modern electronics, sector 34-a, chandigarh, punjab, india. And on 11/6/18, i transported my led to their center as per their suggestions where i was informed about the replacement of the t cone board.
So they gave me the time limit of 4 days for the rectification of the fault.
Today it is 25/6/18. Almost 15 days have passed and they haven't cleared the fault.
And on the phone call i always gets the same kind of response theyalways procrastinate the repair. Also the staff of the center especially mr. Sukhdev singh
Doesn't got etiquettes for behaving with the customers.
Please clear my led fault as soon as possible.