Hello, We filed I 539 for my parents B2 stay extension on Apr 2nd 2019. I have FedEx receipt confirming delivery of my application on 3rd Apr 2019. Till date we have not yet received USCIS receipt nor cheque was cashed by USCIS. We called USCIS multiple times, they are not able to locate application yet and also emailed there lockbox support, awaiting for there response. Now that my parents I 94 expires on 10th May 2019, do you suggest us our next course of action. (1)Should they leave or continue to stay even post 10th May, if they do then will we have any Issues in future(2) Are there any alternatives (3) Is it taking long these days even for receipt, usually how long does it take? Please advice. Thank you.