£14.99 one off payment!!
(Please stop editing this it is not £14.99 a month it's a one off £14.99 payment for a year to argos when you buy the sim). Thankyou
Free to collect in many argos stores or £3.99 for postage.
For £14.99 you get 500mb of data a month for a year.
I think this is a fair deal to keep a tablet or mifi going for a year all in one go. Its less than half the price of the old t-mobile 6month web hack and official.
If you are only going to use less than 300mb a month you might do better to get a three data freedom sim (200mb a month free and 1p mb over that). If you want a gb a month you might do better with one of the three 12 months 12gb sims posted here for about £25.
If you use the 500mb in a month it will stop but I think you can buy a top up somehow if you really wish for the rest of the month.
£20 (Extra: double speed 4G) 4GB
£30 (Extra: double speed 4G) 10GB