"""On O2, getting topped up is easy. When you buy this top up, a voucher number will be sent to your email address. You can redeem this by calling 4444 free from your o2 pay as you go mobile. All you have to do is simply follow the instructions by entering the voucher number. You'll then receive a message from us to confirm your top up has been added.Terms and conditions: Non refundable. T's and c's apply: see o2.co.uk/terms."""