You can give me also a chance: mymicrostockupload.com. In the past I´ve tried to solve the problem with the categories but without a API from each agency it´s not possible. You can add some categories inside the IPTC metadata but no agency (exception fotolia) read this data. As a developer you have no chance to do this job :-(

I see this often, when I upload pictures on weekend. Maybe the automatic algorithm is working on weekend.
What is your experiance when you upload rejected Images again? I´ve never tried.