I am sorry for the trouble you are facing. You actually already reached the last resort to restore your email back. The good thing is Microsoft has responded to your request and asked for more information to prove your ownership.
Did you ever associated you mobile with the account?
Okay do you mind to let me check the recovery options of your account from my side?
We are trying our best to help you. However, if for any reason you are not happy with the service, you may call JustAnswer Customer Services to ask for the refund. I am sending them a note as well to push the request.