Transmission blown due to Valvoline

I took my car to get an oil change, which I do regularly and they were all insistent about the transmission fluid. I did a quick google and saw it was 32,000 since the dealer did it. Total miles are 100k. I agreed and a week later the car chugged and stopped. Luckily I didn't get into an accident! The transmission is blown and Valvoline denied claim because the dealer did not say "the wrong fluid was put into the car" I paid diagnostic fee to dealer. Dealer wants storage or get the car now. What do I do ?