Build a clinic booking schedulling system...

We need to build an appointment scheduling system for a clinic, user must register himself in the system, users should have the option to check available services prices about clinic… after knowing available services and prices, users checks available slots of the week and schedulle and register to one available slot in monthly calendar (he should have the option of paying online via paypal or paying when arriving to clinic). After finish process user must receive an email confirmation from clinic. There must be like an admin panel where clinic can change services and prices or confirm or deny bookings (it should have an option to auto confirm bookings)... as an extra it could be nice that we can send an sms as a reminder to the user one day before the appointment...