Tata Motors — My warranty on Nexon short by 1 month

I Bought Nexon with SELECT CARS, Hyderabad.
When I go for first service, I came to know they mentioned my purchase date one month backdated.
When I approach SELECT that will be ok and he said it will be like that as they hold the Vehical for me almost one month which they not mention warrenty will impact for me.
Now they are not changing the warrenty date with invoice date.

I am doing followup from almost 6 months and not resolution yet.
TATA moters blaming SELECT cars and select blaming TATA.