I happened to go for a local HVAC company last year when my heat furnace started stuttering and did not turn on.
The technician spent an hour to ‘find’ the fix and replace the ‘faulty’ parts which cost me upwards of $400.
The issue came back a couple of weeks back and I happened to call an ‘old-school’ HVAC technician who went through the electrical diagrams on the front panel and doing a rigorous and methodical test on the 30 year old HVAC system and guess what. It didn’t relate anything to what D&D replaced last year and he only charged me $150 after spending 2 hours on it. I paid him $200 for the way he found out what the real problem was.
Sadly, common sense troubleshooting is a fading art.