Unwillingness to compensate staff member

Upon the date of my resignation (end of May) several hours I've worked were not approved for payment. I have been told that everything was approved and would be receiving my money on the 20th of June, yet I still have 31 hours outstanding to me. To date, management refuses to assist me, and I'm expected to forfeit my right to be compensated, even after threatening to make this ******* public. I am no longer a staff member, but am expected to run around at my own expense to be compensated for my own overdue money. It's pathetic that such a large entity cannot pay their staff members.