Did you try making them put dates in writing? I had a guy who kept blowing me off until I made him sign a timeline. Now he calls me to confirm appointments.
My buddy had a landscaper who ghosted him three times. He finally made the guy text him the exact day and time for the next mow. The dude actually showed up that time. Guess having it in writing made it real for him. My friend says he does that with everyone now.