Absolutely, positively the most horrendous service.
We had 2 100 gallon tanks on our property with Heller's when we moved here. Thinking we were stuck with the supplier, we used Heller's for 3 years, dealing with abysmal "customer service" (they hate answering the phone and getting a delivery to you) and extortionate pricing.
It would cost easily over $400 to fill both tanks. You absolutely MUST have a $0 balance before you get them re-filled.
After paying off one such balance of $463, we scheduled a delivery. A few days after, we got a flyer for a competitor. After speaking to them on the phone, and asking about their pricing, we realized we can pay $100 or LESS for a top off - no waiting until the tank is low! Imagine that!
So after we called Heller's, explained that we are going to switch to someone else, they verbally (BIG MISTAKE on our end) said that they would remove the tanks, measure the difference, and pro-rate us. Ha! That never happened!
We were then served a court order to pay them or lose our stuff. We lost the court case (since we had no proof of the agreement), and sure enough the sheriff came and took an inventory of stuff in our home to settle the $700+ bill. Heller's couldn't be bothered to call us (or answer their own phones) and settle this. They are a bunch of rude, crass, shallow, and unscrupulous business owners.
Buyer beware! Cheaper alternatives are out there with companies that WANT to keep you in their good graces.