What to do when visa is in administrative processing and PhD program is starting?
The US state department says that wait times for administrative processing are usually less than 60 days, and they don't allow complaints or inquiries before those 60 days have passed.

July 17th sounds really late for PhD admission. You should have applied for a visa when you were admitted, probably back in April, or May at the latest, especially if you are in a country likely to have more scrutiny of visas.

You can talk to your department and inform them of the delay and ask how they would like to to proceed, but this seems like it falls under the category of "your fault" and there isn't anything your university can or should do to expedite the process. If your visa was denied for some incorrect reason (like they didn't believe you were admitted as a student), then the university would be of more help.