Are you charging a service fee for your online patrons but not when you sell tickets in-house.
This will discourage patrons from purchasing online, which is the opposite of what you want to do.
Some of our clients are encouraging their patrons to purchase online by adding more of a service charge for in-house sales and less of a service charge for online sales. The whole purpose of online sales is to encourage your patrons to purchase tickets for themselves without taking up your time. This leaves time for you to help those patrons who really do need help.