Automatic Transmission Cooler problems of the 2009 Nissan Xterra

I purchased this 1 owner trade in 4/11/19. As of 5/9/19 I started to experience pronounced issues with losing power around 40 mph . Diagnostics confirmed that it was due to a leak in the cooling coil which resulted in coolant in my transmission fluid which damage the transmission. I have filed a claim under the class action required extended warranty. As I was unaware of this issue and didn't know what was happening and honestly afraid to find out since I still owe 5000 dollars on the car I put off getting the diagnostics. The final straw came when I was merging onto the highway and lost power trying to merge into fast traffic. I finally called a local repair shop for diagnostics on 5/31/19 and took the first available appointment on 6/4/19. I was told there may be an extended warranty and to call the dealership. The dealership confirmed the diagnosis the next day 6/5/19 and Nissan is reviewing my claim. I am praying they won't deny it because the diagnostics were completed a couple business day after the extension expired on 5/31/19.