Hi back357,
I’m not supermax of course but I can answer your question 
The Dreamfoam mattresses are fulfilled by Dreamfoam themselves (not by Amazon) and are not returnable (except of course in the case of a defective mattress) and there are no comfort exchanges except for their Eurotop latex mattress and their Total latex mattress which offer comfort exchanges (with a minimal charge) for the top 3" latex layer.
This is part of the reason for their low cost because all “free” or “nominal charge” services offered by a manufacturer or retailer (comfort exchanges, refunds, free delivery etc) are all built in to the cost of a mattress. Deciding on how important each of these options are and any “risks” involved are part of each person’s “value equation” and part of the many tradeoffs involved in every mattress purchase whether locally or online.
Hope this helps
Phoenix