Treasury Services Inquiry If you have any questions regarding our products and services, you can contact us at (574) 235-2003 locally or 800 399-5592 toll free. To report a complaint or suspected misuse of your accounts, please call us toll free at 800 513-2360. You may also contact us by typing your questions or comments in the box below. Be sure to include your email address so we can respond to your message. A 1st Source customer service representative will contact you within one business day. When possible, please provide all applicable information. If information is not applicable, please enter "0" or "none".