Once you have already booked an event the best way to get in touch with the event is to send them a message from your booking request.
First login to your account at eventhub.net. Then click the drop-down and select My Event Hub to be taken to your My Events page which will list all your booking requests.
Located on the top left of each booking request is a Message Event button. Clicking that will allow you to send a message directly to the event the booking is for.
Just fill in the Subject and message from the window that pops up and click Send Message when you're done.
This message along with any replies it receives will come into your My Messages inbox located on the very top right of your screen.
You will also receive an emailed notification to your accounts email address when a new response has come in to notify you to check your messages.