Onida LEO4000F 101.6 cm (40) Black Patches

I purchased Onida TV “Onida LEO4000F 101.6 cm (40) LED TV” from Flipkart on 25-05-2015 Order ID: OD002938843456788500 before warranty expiry I have done extended warranty for 1 year through AMC EWC No:-2015019041 which is valid till 24/05/2017 from Onida and paid Rs.3650/-. Now I have noticed there is black patches appearing on the screen for the same I have logged a Case on 19 Jan Onida case ID 1701E716380285. After multiple follow-ups approx two months later now on today 14/03/2017 they are saying part is not available with us hence we can’t replace the part. Instead of resolving the issue they are offering me to buy a new Bull Shit Onida TV and giving me 25% discount on the product. Why should I buy a new TV and again I will pay for new TV as I have already done AMC.
What is the benefit of doing AMC you should resolve my issue or replace the TV, you guys are cheating the customer and charging amount for nothing.