College didn't receive the submitted deferral supplement form

Hi, My son applied Georgia Tech as his only early decision, got deferred. He added some required documents and submitted the deferral supplement form before the due day. But the Georgia Tech didn't receive it. He has been rejected. I talked to the lady in the admission office; she said they didn't receive the deferral supplement form, she let us to prove we did submit it. My son checked his emails and application account; he didn't get an email after he submitted form. The emails we have are my son sent to my husband which said he already submitted form from internet. I think probably their computer system has some issues. What can we do now? Please advise. Thank you.