Long enough for the year warranty to end

For $1200, I expected to get more than 3 years from this mattress. I wake up every few hours with lower back pain and can barely stand in the morning until I've stretched and gently removed myself from the bed. When I try to roll or move during the night, I feel like I'm trying to get out of a hole. I contacted mattress firm about this and the customer service rep said that he didn't know how much money I spent on the mattress but I get what I pay for and that my warranty was ended after a year. Basically that I'm out of luck with any support. Super unhappy and kind of at a loss.