I’ve had this happen a lot. Probably the majority of contractors who have promised to give me estimates just ghosted me. I would not bother to contact them and ask what’s going on. My view is, if they’re this flakey before they even have the job, when they’re presumably trying to make a good impression, I don’t want to see what they’re like after I’ve signed a contract.
However, that being said, I don’t think that what the OP describes qualifies for disqualifying the contractor quite yet. A promise of 3-5 days and no contact after 7 (working) days is still borderline acceptable in my book. Unexpected things happen, and yes it would be better if they could predict their availability to write up the estimate a little better, but if they got me the estimate in the next few days I would excuse the delay. But after another week, they’re off my list. For a $5-6K job, I will be getting at least three estimates anyway.