Hi bluemoose,
I don’t know what their policy is on returning a second mattress but I would certainly check with them.
If you are able to return the mattress then subject to first confirming that any retailer or manufacturer on the list is completely transparent (see this article) and to making sure that any mattress you are considering meets the quality/value guidelines here … the better options or possibilities I’m aware of in and around the Houston area are listed in post #2 here.
Phoenix