I've had a hot mat experience too. Florida summer sun, the worst!! I bought the big one at Joann's one fine, HOT day, with a coupon of course. Stopped to get gas, the mat was flat in the trunk. Got home, the mat had buckled in so many places I gave up counting. I've tried putting it out on the tile next to the pool in the hottest sun. Nothing! If possible MORE bumps. I then put a towel over it and loaded it with my heaviest books, this was recommended by a quilting friend. NOTHING! Then I ironed it, first placing a towel over it. It didn't work. What should I do with it now? All those bucks, down the drain. I'm upset too, just as you must be.