We sent in a service request via online. Here is the verbiage for our biometrics appointment inquiry:  On 03/05/2018, you or your representative contacted USCIS concerning your I-751 / CRI89 to notify us that you have not received your biometrics appointment notice. Below is a summary of what we found and how the issue has been or may be resolved.  Thank you for your inquiry regarding an appointment to have your biometric images processed at an Application Support Center (ASC). We a