Just got the sim only double data offer, you will see the double data deals are a little bit more than just a regular update, ie £8 for 1GB where on the double data offer £9, But to get it I had to phone 789, as i have gone to 4G they had to do a finace check (only been with them for 5 years) but that life, they signed me up in 5 minutes, you cant get double data on line,(I think thats right), it comes in effect at your refresh date. hopwe this helps you only have until the 28th, good luck.