I never let a service tech leave without confirming they have done their job. If they must leave, I would expect an explanation and a followup.
What happened to you is completely unacceptable. Sadly calling 800-comcast will leave you feeling a bit empty.
I have had Comcast is MA and TV and would say mostly it is a good experience. I have had minor issues over the years, but always resolved.
If I were you and you have time I would have a little "fun" and escalate this issue. If you are going to use Comcast, see if you can use your experience to get some "specials".
Hopefully you do not get a bill for your experience, i.e., install fees, HBO for a day
