First, check to be sure that your Medicare Part D plan is effective - your Medicare Part D plan should be effective the first day of the month after your enrollment.
Please try to contact Humana New Member Services at: 1-888-839-7316.
Should you need to fill your prescriptions and the status of your Medicare Part D plan is not yet active (although you have enrolled on time and your plan has an effective date starting on or before this month), you can purchase your medications and pay in full and then send a copy of your enrollment form showing your Name and Social Security number along with copies of your receipts to:
Humana Claim Office
P.O. Box 14601
Lexington, KY 40512-4601