Wrong missionary return date

Our son returned home early from a prosyliting mission and switched to a service mission. When filling out his BYU application, they have that he only served his mission for the few months he was prosyliting and not his actual ending date.
I can't edit the date on his application to show he served the full 2 years. How do we fix this? Who do we contact?

Have you tried contacting the admissions office? It appears this page has a general phone number and an email address: https://www.byu.edu/admissions

Oh, better yet: This page has a 'Contact Us' button for admissions, application help: https://enrollment.byu.edu/admissions/application-help That button brings up a page with phone numbers and message/chat/meet options.

Thanks, we've reached out and are still waiting. Will have to try chatting when they're in office. Thanks again.