John's Home Comfort heating and Cooling

I called John to fix a minor problem with the furnace. He arrived to my house and, after looking at furnace for 3 min, told me that this is a major problem that will require a lot of work. Then he told me that my piping for hot water tank is not up to standard and issued the red tag (meaning that if it's not repaired within 20 days I will have gas disconnected). Then he told me that only he can clear this red tag... so it was poor extortion. Plus I got to pay $150 bill for his 3 min visit. Called another furnace technician next day, he charged me $115, fixed the problem with furnace (it was a minor tune-up) and cleared the tag, which apparently was issued "erroneously".