Mobile Mechanic Demanding Payment For A Job He Did Not Do Correctly, Has Come To My House Twice.

Location: Mi, USA.

I wanted to get my full suspension checked for my struts/shocks/ball joints on my car. I hired a mobile mechanic and he said it'd be $80 for a full inspection. I told him "Thats fine." he came over. I try not to be a judge of character based on appearance but he looked shady and kept rambling about customers. He looked at the space between my tires, had me turn the steering wheel and told me he could just "tell" that my entire suspension system including shocks/struts/etc needed replaced due to visual inspection (didnt look under my car, literally only looked behind one tire.) I told him I wanted a full inspection which would involve a jack etc.

I don't know too much about cars but I believed that a proper diagnosis for a suspension system would require a test drive, looking at tires, checking the struts themself. He then told me he will go ahead and order the parts and I told him no, I would like to take my car to another mechanic to get the suspension checked because he did not do a full diagnosis. He said I owed him $80 for the diagonosis anyway. I refused.

He left, and then came back a few hours later and demanded payment, I once again told him no and he left. About an hour later he has driven past my house a second time. He then messaged me that if I don't pay he will look into legal actions. Am I required to pay someone who did NOT diagnose my car beyond looking behind one wheel, or am I protected if he did pursue legal action? I dont believe him pursuing legal action is worth just $80. If I agreed to a full diagnosis over text how legally binding is that?

Additional information, I have the entire conversation and him checking my car on my porch camera.