Confused about what you're expecting. You don't consider a travel voucher, received within hours of submitting a complaint, an adequate reply to a generic complaint about a generic delay? Personal apologies are not really de rigeur in the airline business. It also doesn't seem worth it for JetBlue to pay people to craft custom responses to each complaint about things that go wrong on a typical day. On other airlines, you might get a canned reply without the travel voucher, so I'd be happy with that personally.

Also, delays are calculated by arrival time, not departure time, so my guess is that your delay was under 3 hours.