Simply Service Federal Credit Union 1842 5th Ave. Belle Fourche, SD 57717 Click here for a map. Phone: 605.892.4631 Fax: 605.892.3181 contactus@simplyservicefcu.com Report Lost / Stolen Card To report a lost or stolen ATM / Debit Card during business hours, contact us immediately at 605-892-4631 To report a lost or stolen ATM / Debit Card after business hours and on weekends: Call 1-800-236-2442