I was given an HTC phone on Orange network about a year ago, so bought new Orange PAYG sim card at the time. Dont use it that much, topped it up twice so far, but when I tried to top-up again on line today on orange website from my PC, I get message that the mobile number is invalid! I repeated this three times, same result. Anyone able to advise me why this should be please? I am a bit mystified!