Booking System for Banquet and Concert Hall Rentals with Date Availability Check

I run bookings for a group of banquet halls and a mid-size concert venue, and right now everything is coordinated by phone calls and a shared spreadsheet that two managers update independently. This has already caused a double booking twice this year, where two different clients believed they had confirmed the same hall on the same evening, and untangling that mess in front of both clients was embarrassing and expensive. I need a proper booking module built for our website where an event organizer enters the date they want, the expected number of guests, and the format of the event — banquet, wedding reception, concert, corporate conference, birthday — and the system responds with a list of halls that actually fit that guest count and are free on that date.

The core requirement is reliable date locking: once a booking request for a specific hall and date is confirmed, that combination must be blocked from being offered to anyone else, including inside the admin panel, so a manager can't accidentally re-sell the same slot. I also want time-window logic, since some events only need a hall for a few afternoon hours while others book the whole evening, so overlapping windows on the same date need to be handled correctly rather than a blunt full-day block. A simple deposit or hold status before a booking becomes fully confirmed would also help cut down on no-shows.

What I'm looking for from a freelancer:
— a booking form with date, guest count and event-format fields, wired to a live availability check
— an admin view showing every hall, its calendar and current bookings at a glance
— double-booking prevention enforced at the database level, not only on the interface
— basic staff notifications when a new booking or cancellation happens
— clean, mobile-friendly design matching the rest of our site