If you have a problem or question relating specifically to the event you are attending, you can reach out to the event organiser. All event organiser contact details can be found via the event pages, or by checking your conformation email, which you receive when purchasing a ticket.
Failing this, some organisers link their website on the event page. To find an organiser event, you can use the event search bar. If you are still struggling, reach out to Xentra Support, who can find the contact details for you.