Kayak Rental Company - ON / OFF Line Rental Booking Sheet

We are a large Kayak and Surfski Rental (HIRE) company. We are looking for a program to be built to allow for on and off line bookings for our rental operations. We have 100 different kayaks - we operate 7 days per week - bookings start from 7.30 am to 5pm with thae last booking available being 4pm to 5pm. Bookings are a minimum of 1 hour each. Customers can book from one hour up to All day. we process about 15,000 individual bookings per year. we need easy access to change the different models of kayaks. We will use this program to take bookings via the phone from to our booking agents as well as via our website for one off and regular customers. We are currently in the process of having our website re-built using Joomla The interface needs to be very simple and user riendly for internal staff and the customer. we are looking to expand in the future to different sites and would like this to have the ability to add different sites moving forward. full payment will be made when we are 100% satisfied in the program, there are no bugs in the system, and all related files are passed on to us. We could also agree to an ongoing development fee as the programs needs expand over time. Thanks