PHP Script needs modifications

Hello. A client of mine just purchased this script: [login to view URL];cat_id=3&image_id=67 It is fully up and running on his server and works great. Now we just need a modification in functionality: Instead of charging the employers for posting a job and contacting potential employees, he wants the script to do the reverse: charge the employees for posting resumes and contacting employers. I'm sure it's just a matter of switching a few database fields and tinkering with the code a bit - I know a bit about PHP development myself, but I'm afraid that after looking at the code, this may be too delicate for me to handle - in otherwords, I know how this should be done, I just don't know how to go about doing it. I think this shouldn't be more than a couple of hours of work, tops, for an experienced PHP developer. My company is a one-woman show so I'm on a tight budget, but that won't be my only consideration when choosing a service provider. Payment will be immediate upon completion. Good luck bidding!