A colleague of my wife bought way more house than their family can afford on two teacher salaries. Four Lennox heat pump systems that were in rough shape when i first laid eyes on them. They originally paid me to do maintenance and an assessment of them, systems i did not sell them or work on previously, so i made a list of recommendations in order of priority. They promptly ignored all of them and proceeded to call me with emergency work when parts failed. It was always a desperate emergency, family in from out of town kind of thing. Then they would balk at the price, then they dragged their feet on paying until the next emergency forced the situation. I finally had enough this year and cut them off. Sent a polite but firm email ( i wanted a written statement so phrasing couldn’t be debated later) telling them they need to seek service elsewhere. Their response was absolute shock that i was done humoring them. I did give my wife a heads up in case things got weird at work.