Sailnetīs demise, this suggests...
You might want to contact the Seaward customer service department and explain the situation. I ordered a Seaward water heater last March and it arrived OK. I remember, either on the Sailnet web site or in the confirmation of my order that water heaters are shipped directly from the manufacturer, not from Sailnet. However, don''t know why they would "fire sale" them if they don''t stock them in-house.
If you''re in luck, maybe Sailnet has already sent the order and their payment to Seaward. Or maybe Seaward can make some sort of accomodation. As a supplier to Sailnet they must already be aware of the situation although they may be having their own billing problems with them.