When a freelancer believes they are owed money that the client is refusing to pay, or a client believes he does not owe money that the freelancer is asking for, they can submit a dispute about the milestone in question. ZMZ staff will receive it and attempt to mediate a solution.
Many of our policies on disputes are listed in the Help Center, and users can usually determine how ZMZ staff will settle the issue by reading through those.
Disputes leave a bad taste in the mouth, so we always recommend that users try to resolve conflicts themselves before appealing to the admin.