Chris

Changing your payment method doesn't cause your phone to get cut off, so he won't lose the number simply by switching to monthly payment at the Post Office or by debit card. And when we got married, Mrs T's phone was transferred from her mum's account to mine without any bother. That was on Orange though, I don't know about 3. I would have thought they would be so keen to keep you, they would not want to put obstacles in the way. The worst you can expect, I think, is a monthly surcharge of a couple of quid for not paying by direct debit, and maybe a one-off admin charge of about £10 for moving a phone from one customer account to another.

I have also successfully moved an Orange phone from contract to PAYG, but you can't do that within the initial 12-month period you own the phone of course.