Don't miss out on £5 extra credit ? just for going large. Change up to the £15 Data Big Bundle and instead of 6GB, you'll get 15GB, plus unlimited calls and texts. All to use over 30 days. Text 15DATABB to 21300 to change now. Once you've set up the change, top up your balance to £15 or more to buy your first bundle. Terms apply. To stop these messages, call 2220