Develop hotel booking function using GTA xml API

We are migrating our Travel website site to have hotel, transfer and sight seeing bookings. We are using GTA's hotel, transfer and sight seeing data provided by XML API's from GTA. We require skilled GTA XML developer who can create booking function using GTA's API with ASYNCHRONOUS method. The website layout, mysql database and functions such as search data has already been developed and now looking highly skilled php/mysql/xml with GTA API's developer. The scope of this project is to develop only a booking function rest of the development will be done ourself.