UPDATE
I forgot to update this earlier, but there has been some development.

Propane was FINALLY delivered on January 8th (Tuesday)!

The day after I posted this site, January 9th, a gentlemen from Suburban Propane contacted me via phone.  He let me know that he was very sorry for the way that the situation had turned out and that Suburban Propane strives to satisfy every customer.  He said that Suburban Propane should not have told me that there was nothing that they could do and that they should have addressed the issue.  At the end of our conversation he said that they want me to be a long-term customer and have my business in the future.  He's going to look at the invoice and see how he can adjust it and will get back to me over the next few days.  That was January 9th....it is now January 17th.  I plan on calling Suburban Propane today for a followup as the invoice I received is NET10, which makes the due date the 18th.

I'll let you know how it turns out!