I have a maintenance plan for furnace, and auto-delivery & auto-pay for oil. Both of these arrangements offer discounts on parts/services and oil, respectively. However, Tevis invoices only show one price. I recommend Tevis invoices show both the "before" and "after" cost when discounts are applied. I like the option for auto-delivery with confirmation (I receive a call from Tevis alerting me to my likely need for oil & I then call Tevis to confirm I want a delivery). I also appreciate they deliver oil using a "light truck" to help protect the old country lane to my house.