I can only imagine how frustrating that must be! However, just so you know, yhou should not count on any posting you make in this forum being seen by Dreamhost staff - this is a “customer to customer” forum only. Occasionally, a Dreamhost staffer might visit, but you can never count on that.
By responding to the support email, your ticket should be kept alive, but if you do not hear back from them do not hesitate to open another ticket, so they know your problem is not resolved.
In the meantime, have you tried logging in with your “m1234567” account user id? I suggest trying that, and see if it lets you in. If it does, than the problems is most likely in the firstname.lastname@example.org lookup function (which they can fix) but at least you will be able to get your mail while they get it sorted.