Complete modifications to a real estate website - including online payment module

We have a part completed project which we require a coder experienced and very proficient in php and Ajax to help us finish. The project is to complete the modifications of an existing properly/real estate listing website to: - change the way the users list the properties - offer them additional services (and charge the appropriate amounts as required) - restructure the flow through the sign up pages - to complete a property listing the client must either choose to buy the alternative services or provide information/expiry date and upload a document - the site admin must be able to monitor the listings and check that all the correct files and fields have been uploaded. If they have they can change the status of the listing to put it live. - the certifications that the user buys or uploads that have an expiry date will be modified so that a series of emails are sent prior to the expiry date (4 weeks before, 2 weeks before and on expiry date) - add in/restructure admin area to allow admin to search filter the property listings - integrate with a payment gateway - add in content pages If you are interested in this project please provide evidence that you have a solid experience with complex php/ajax driven projects.