My son has appealed a decision for an overpayment from social security. We asked for a formal hearing and it is over 8 months. Is this normal?

My son and myself were collecting ssdi under my name. I went back to work and they charged me 30 plus thousands of dollars for an overpayment, even though I repeatedly went to the office to report my earnings. My son who is still disabled and collecting on his own now has been charged with $19,000 overpayment. They also owed us $9.000 retroactive which they stated was put towards his overpayment. This never happened. We asked for an appeal in October 2018 and we still haven't received a date. I can not understand if he is still able to receive disability then why is he responsible for this overpayment. I am so frustrated and going to the local office of social security does not do anything. Please advise us what to do.