united propane inflated price for propane because they lock you into a contract for using their tank millersville, Maryland

Ive owned my home over 12 yrs and United propane salesman gladly installed a tank for a minimal charge as long as I purchased from them all of my propane. this was not a concern or at issue even if it was marked up a bit for the expense of the tank. but now the price is about 50 cents or more higher than if i owned my own tank , ive called everytime and they have adjusted the price, but the last time only met half way. I want them to remove the tank and they have so many fees associated with it that they are punishing you for takign your business elsewhere. ive asked if I could simply buy my tank and let them fill it ,of course at market price. they said they do not sell tanks anymore. I  want out of dealing with united propane but it is so difficult.