Have you contacted the team through Live Support? I think it can be the fist one you need to try. Even if you reported the case in this thread, the team may be not always active here.  ;
If you have no problem to withdraw your balance in the past, there should be a problem with the phone or the phone number. Are you sure that the phone number is still active? It is a bit confusing that the message said for registration. I guessed you have registered with the phone number in the past, right?