reservations plugin?

Hi, i’m running a business with several employees that need an online booking service. I’ve found several but most are them are for booking in general. I want to specify the employees, hours, availability etc. Make sure that no one can double book the same person twice. can anyone recommend a plugin of sorts..one that also emails that employee when he or she is booked for a time slot. Also appointments are limited to 30 minutes per booking.