What you are facing is a not so effective mailing process. To deal with the bureaucracy, below are some suggestions:
1) Contact your US Senator's office for them to do congressional inquiry. They are usually very effective to get you some answers and follow up until the matter is resolved. Below are their major office numbers. They should be able to get you to their intake staff's telephone number. You only need to get one of the senators to help you.
Capito, Shelley Moore - (R - WV)
172 Russell Senate Office Building Washington DC 20510
Manchin, Joe, III - (D - WV)Class I
306 Hart Senate Office Building Washington DC 20510
2) Find an attorney practicing in the area of social security disability. They are usually on contingency basis. At least, you can have a head start on where to go next.
3) Walk into a regional, local social security administration office and talk with a representative face to face.
But you cannot ignore the notices. Write back to the Philadelphia, PA responding to the notice and say what you stated in this posting. Hopefully, by that deadline, the above actions 1-3 would have gotten you some break through.
Please feel free to follow up.
Fiona Chen, MPA, Ph.D., CPA, ABV, CFF, CITP