Dear Security,
ERISA requires that all plans such as these must provide you with the details of how to file appeals. If you contact them by phone and ask for the procedures and they don provide the information, then you can appeal by formal letter.
You need to give them at least one chance to respond to an appeal, but you may have to end up suing them.
In the past, appeals to a denial of benefits are included in the denial of benefits document /statement you receive in the mail.
If you did not receive a denial of benefits in the mail or you did and the appeal process was not included, then you will have to appeal by letter or file suit.
Attorney
JD