How to handle furniture switch up?

We really really needed new mattresses. Our mattresses had mold on them so we needed new mattresses. We went to rooms to go on black Friday lady showed us a nice temperpediac. It was buy on get one free. She checked credit we were approved then she dropped us off with someone else who gave us payment options we sign stuff & go about our day. I was paying more attention to the price, not the furniture. Mattresses get here they look nothing like in store so I'm thinking maybe the mattresses have some cover over them on sales floor... Delivery people leave I sit on it this isn't a temperpediac... This thing is like laying on the fucking floor. We look at the fucking paperwork & the temperpediac is t on there it's some random mattress we've never heard of. All we looked at was the temperpediac because we had been wanting one & they had a really good deal. Idk what to do I'm ready to cry & feel scammed my back hurts extremely bad, my husband who's back is messed up from a motorcycle accident is in lots of pain. What do we do???