Refuses to exchange the bed mattress, which is under warranty

I bought a rest assured bed last year, April. Apon buying it, the sales person advised me that the bed has a two year warranty and if I had a problem with the bed, it will be exchanged. About three weeks ago I noticed one side of the mattress has gone in. So I contact the bed doctor, who addressed this matter with rest assured. Rest assured contacted me and told me that they need someone to come to my home and have a look at the bed. It's been three weeks and no one has come to look at the bed. I paid alot of money for the bed, I don't see why rest assured can't just exchange the bed, like the rest of the bed distributors.