Today I ran out of data and my data does not renew for another week. I contacted EE online (log into your EE account and wait for the pop-up towards the left hand appear) and asked for some extra data, and was given 500gb. I am on a 2gb sim only plan, so if you do run out it's worth asking, as the charge for extra data is extremely expensive.
500MB, not 500GB. Just for those that can't be bothered to read further down! *We all make mistakes!* :)