Middleburg, FL 32068. Main: (904) 282-6331 Billing Fax: (904) 282-4117 Hours: Monday - Friday | 8:30 a.m. - 5:00 p.m. Disclaimer: Visa, MasterCard, Discover and American Express are accepted at all locations. Collection action will be taken for any charges; including those that insurance has not paid, older than 90 days..