To find out the details for the agency(s) involved in your booking, go to:
Manage, Booking Requests on the Menu
Search by the unique venue ID number (If the booking was not done by yourself, switch the dropdown to All Bookings)
Click the correct tab (e.g. Confirmed if it's a confirmed booking)
Select the right booking and it will open up the booking details
Scroll down
to see the Agency contact details in the Contact & Stakeholders section.