O2

I cannot receive or make calls since I changed my 02 plan to pay as you go. It's top up but all the calls I receive go straight to voicemail (that I cannot check) and all calls I make simply do not work. Does anyone know what it could be?

I recently changed my monthly plan to a Pay as u go plan, once I did it, I topped it up with £20. I haven't used my number neither for calls or internet and now my credit is £0. Can someone explain me why? Isn't the pay as you go plan consist in payi...