Bookingssystem HIGH SECURITY!

We are a small company therefore I can't promise the project will be done. Here it comes: We are looking for a bookingssystem with a front end and a back end. front end: A iframed page from my server on their website with the following: People choose what they wanna book than they get a colored datepicker Green means possible Orange means discount period Red means unbookable people can't click that dates. after they have done that they go to the payment panel ([login to view URL]) we have a easy api for payments. and after paying they get a invoice. Backend: This is a multi company project so the owner (me) need to be able to create a account for a new company. The company's need to be able to: See the bookings in a easy and fine view. Add/Edit/remove bookings. Create tax options like: vat etc and bind multiple to their accommodations. See how much they earned and how much places they have sold in total and between 2 dates. Creating accommodations with option to: Set the amount of places Set special amounts and money on special days Set date's where it's not possible to book. The company need to be able to change the invoice to how they want it without php knowledge so maybe with something like word. If the amount of places are booked it will not be possible to book anymore and will get red. Safety is our highest priority! We really don't care about timeframes.