Sansui India — Sansui 75 inch TV not working

Hi Sir, From Amazon I have purchased 75 inch Sansui Smart Google 4k Smart TV on 15th July.
After installation, we found none of the 4k videos is running on the tv. Amazon Prime, Netflix not working. Amazon Fire Stick in USB port is not working.
I called Sansui customer care many times( 15-20 times). They told it is mother board issue and they replaced the mother board with new mother board.
After that also it is giving same problem. Again I called customer care on 28th July and they told, they have escalated the case and a new mother board will be provided.
Now when I am calling Sansui service centre, they are denying that things are not in their hands to solve this issue.
We are totally stressed with the issues coming in the TV and poor support from Sansui and denying the product quality assurance after sales.
This is mental stress to the customer.
We now need the consumer court support to help us in this case.

Serial number : S15231WWS021417