Pay & Go Data Sim

[telboy1938]

I need to use a MiFi Dongle occasionally when away from home but seem unable to locate one that doesn't expire after one month even if I have only used a small part of say 2Gb . Is there a Data sim card that I can top-up when required? Thanks. Tel

[Buenchico]

Some of the offers from '3' include a data allowance with your initial purchase that's valid for up to 3 months but I'm not sure whether that extended time limit applies to top-ups thereafter. (The information should be on their website). However there seem to be no deals without some sort of time restriction:
http://www.broadbandgenie.co.uk/mobilebroadband/pay-as-you-go?showAll=1#featured

http://www.three.co.uk/Discover/Explore_our_products?show=dongles