Protect Yourself - Do This!
When someone comes to you and tries to sell you a service or some repair work, ask to see their driver license. If they don't have one, or refuse - close the door. If they show it to you, check to see that it belongs to the person holding it; make sure it is current; make sure it is from YOUR state. Then use your phone to take a picture of it. Now, if anything goes wrong, you can find them...and so can the police.