I tried contacting a customer service agent and I've read everything but there is 0 solution. I have a huge presentation tomorrow and everything has fallen apart today. I'm working on a project with freelancers and they can't access my file unless they upgrade. We are all being requested to upgrade. I paid 199 on biz account and its still requesting colleagues to upgrade. it's literally 1 folder in my dropbox. I want a refund so that I can move everything to google docs. I've been with dropbox for decades but not being able to speak to someone is beyond frustrating.
Regarding the issue you mentioned, it seems like you upgraded to the Professional plan and not a Dropbox for Business teams one which would allow for a shared pool of quota among the members of the team.
For more information on this, you can have a look here.
I hope this helps to some extent and please keep me posted on your progress, Sarita.