Adding the "one too much" user to your account can kill everyones access (BB-8641)

We had a 25 people plan and one of our admins added the 26th user. He told me that he wasn't informed that this would go above our 25 people limit and was not aware that this would

• set all repositories to read only
• disable any ssh access at all

This caused a big disruption in our daily workflow until we were able to contact support, figure out what's wrong and get an upgrade on the account (the user with administrative privileges for this - me - was on vacation at that time) with some help.

Please, could you make it that:

• it's not possible to add the N+1 user or display a really fat warning that this will basically screw up bitbucket for everytone in the organization?