Modification of a CodeIgniter script

I am looking to modify one of my scripts, which is a Airbnb like site. The script is fully functional and setup on a test domain. What I need to modify is the way the booking engine works. As of now, bookings are made by nights, and so are new listings created. I would like to change this so that bookings can be made on a per hour basis throughout the day. This involves modification of the booking engine itself, including the calendars, the way a new listing is created, the search function and the booking function. When setting up a new listing, the user should be able to define the duration a booking is valid for (e.g. 30 mins, 45 mins, 60 mins, etc), the hours of availability for booking (e.g. 8am - 8pm) and the max. number of bookings at a same time. Once this has been modified correctly, there might be further projects for the chosen freelancer. Payment policy: 1. We will create a full milestone payment upon project award 2. We will release the payment once 100% work was delivered to us 3. If one or more of the described items are not or only partially developed, then you agree to cancel the milestone payment entirely, seeing the project as failed in its' entirety with the reason that we will have to roll back in order to get someone else to redo the work. Please note we are working on a strict timeline, as other projects will be pending on the completion of this project.