I just a got a'new' (to me) phone. I put my current SIM card into the new phone. I can text and call without problem, but can't get/use any data. I tried to start working through the self-serve 'Upgrade your phone' process, but got stopped when it asked for my new SIM card number - when I enter in my number it won't let me carry on as it 'is already in use'. What now?