Emailing or calling is the best way. Personally I would suggest calling first. This is a little bit more 'personal' than sending a message and will allow you to have more of a conversation with your admissions counselor. They are not the ones who make admissions decisions, but they will make a note that you called and it shows you are proactive and invested in your application. Then, follow up with an email just so that you can be sure they have the correct details, and sometimes things get misheard over the phone.
Would suggest doing the same with the staff member who is responsible for coordinating applications for nominations for your senators and congressperson.
Just one opinion/piece of advice