Fix OSCommerce payment form

I have a customized version of OSCommerce with a single page checkout that doesn't work correctly. I'm looking for a developer intimately familiar with single page checkout in oscommerce who can make it work. Should be an easy assignment for somebody expirienced with OC. Before the project is awarded I will require an initial assessment of the problem from bidders so that I can make sure that the provider has the necessary expertise. Bids over $50 will not be considered.