Have an attorney now. Been to Ford 3 x for shifting issue and been there 1-1/2 months

I am paying $43,000 on my truck. I don't believe this problem should be happening. Ever since I got the truck with 26 miles on it, it has been a problem going up hill - it would sputter then, engaging, it would drag. I thought maybe that was an issue until 2d ays ago when I had a mechanic in my truck and he said the transmission is slipping.