The thing is that I've hired guys who do good work -- they're just lousy businessmen. I haven't written about it here before, but the company we hired to replace our windows is the same: calls/voicemails go unacknowledged or unanswered, the sales rep comes late for appointments, his emails look like garbage. It's an acceptable flaw in someone who is only doing "side jobs". But in someone trying to sell his (her?) proficiency to the public? Either learn how to do it passably well or find someone who can help you. If these guys opened a retail store, it probably would not have a sign outside, the place would be dusty, and the receipts would be printed on torn scraps of cardboard.
Interestingly, the two biggest installation mistakes anyone made in our house came from "captive" techs -- people who worked at (and were paid by) the company that sold us the goods. At least in those cases, the guys were smart enough to align themselves with a company which could handle the marketing and the phones and appointments for them. Too bad they still did questionable work.