You may want to ask about a budget billing plan also. We have that for our fuel oil. They charge you a flat fee each month so you don't get slammed with astronomical bills on any given month. At the end of the season, if you have a credit, they refund or, if you have a balance due, you pay it off before the start of the next season.
ETA: Because we signed up with the budget billing plan, they capped the price we will pay for fuel oil this season. If it is less, obviously we get the cheaper price.
I don't know if propane does the same thing but probably worth checking out.