Custom Booking System

Hi Guys
I need a extension for my car grooming shop,whereby people can prepay and reserve a date and time.
Anyone knows of a extension whereby it can:

1. Display a calendar and lets the user know which timings are available and how many slots are left (in 1 hour )
2. If the user books 3 slots, e.g 1-4pm, the backend will deduct the available timings (e.g per 1 hr there are 3 places available)
3. Able to book 3 places for a single time slot per transaction
4. Able to book multiple time slots per transaction
5. Timeslots must have inventory/ e.g 1-2pm (5 places/slots available), and it will display how many slots are left, backend able to configure how many slots for each timing
6. I saw a plugin but its not for opencart (http://codecanyon.net/item/booking-syst ... view/87919)
7. able to link with the standard opencart capabilities such as "coupon codes", "different price for users"

Many Thanks appreciated!