If the activation keeps stopping at 11% for all 3 users odds are it's a mailbox issue. Look at this KB and try see if the example log line matches in your BES logs:
BlackBerry Search Results
Essentially what happens is the ID of a folder changes, like they deleted their contacts folder and created a new one. The BES only syncs with the default folder and not newly created ones. The article will show you how to check for the issue. If this is the issue I'm surprised that RIM support didn't find it, it's the first thing I looked for when activation stopped at 11%.
If that's not the issue just search the
BlackBerry Technical Solution Center for Activation 11%. You should find some articles that may help.
Keep us posted.