Chances are, and it's not 100% sure (it's just my own layman's experience) that work is proceeding downtown. Typically when Network Vision work is going on at any given site, phones connected to that site will experience unstable service in all areas (Voice, Text and Data).
The other think to bear in mind is that since downtown is heavily populated, many phones may be trying to use data at the same time which, of course, drags things to a snail's pace - if you're lucky.
Considider dropping some scratch to the site and become a sponsor. You can find out how here: ( http://s4gru.com/index.php?/topic/1195-information-about-s4gru-sponsorship-levels-and-how-to-become-a-sponsor/ ) It doesn't take much - give what you can. You'll have access to lots of great information.