No lifetime warranty

I bought a restonic orthopedic gold bed in 2017. Was so proud of my investment. Sadly, almost 3 years later the mattress is lumpy and sagging and the stitching has come loose on both sides. The store i bought it from, Poco Sandown in Sunningdale Table view, has closed down. I've sent an email on Restonics website but have not received any response to the matter. Hope someone can help me. Thank you Volenté