Sony India — kdl43w800c panel failure - strong suspect defective piece has been sold

Dear sir,

During oct 2017 my sony led panel was damaged due to unexpected situation.
Model - no - kdl-43w800c
Serial no-4514768

I had raised the complaint to sony customer care and they have assigned ticket to sony authorised center named new sai electronics in pune. After investigation by sony technician it has been found that led panel has damaged and i have been suggested to replace led panel which was ordered by authorised sony center. After receiving new frontend led panel costing rs. 23945/ from sony india it was fitted by technician and led started working.

After two years i am facing picture quality issue as it is showing some distorted lines on display. I had raised complaint to sony india during dec 2019, it was assigned to same authorized center and technician suggested it could be either tikon or front end display issue. Technician has tried new tikon but problem still persist and advised to order new panel again. It will cost again approx rs.24000/.
Now it has been observed that sony being reputed company how can be new panel will be having display issue within 2 years without any manual intervention? It has been also observed that the panel which was ordered during oct 2017 and received from sony is having serial no 4515313 written on white paper pasted backside of panel. As per my understanding this kind of different serial no never been assigned to new product which differs from my panel's serial no.
I am suspecting that the panel which was delivered to me was defective piece which was repaired against someone's led.
Sony india offered me 50% discount but i need full replacement of the product because this is defective panel they had sent to me. Please help me on this.