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?