Amerigas Locked my Boiler, tech cant really asses it, says I need a new one....Thoughts?

So my old Wiel Mclain Gold GV started pumping CO and Propane into the house. After the fired dept came, Amerigas put a padlock on it so the gas cant be turned on. Tech couldn't really asses what was going on with it, because of being locked out, but assumed that the heat exchanger had a crack or was broken. Says I need a new one. Curious on your opinions, this is an 18 year-old boiler.

Also they are suggesting we get a Weil Mclain GV90+4, if you have any opinions would love to hear them. Thanks