O2

My dad has just upgraded his phone and needed a different sized sim card. We have done the sim swap and the phone number has transferred to the new sim card in the new phone and the old sim card has stopped working however it has not transferred over...

Can anyone help? My father has had a sim only contract for years but he has decided to change to a monthly contract. He saw a deal in another mobile phone shop on O2 network but they couldn't change the contract over as they are saying it is a busine...