I am looking for a mattress for a cousin of mine who has an adjustable bed but the mattress is no good. He is a heavy person most probably around 25 stone maybe just a bit over. I don't know if an ordinary mattress is ok for these adjustable beds or if you have to have a special one. How soon are you able to supply a mattress and do you remove the old ones. It is for a 4' x 6" 6' bed but only one person sleeps in it.