Currently I am using EE with a 15GB per month limit, I can upgrade to 30GB per month with EE but they don't seem to do more.
Using my ADSL I normally use about 125 GB per month so Ideally I would like something that allowed that or more.
Is there such a thing available?
You can just buy additional data packs on EE though the My EE side. Each extra 10GB is £15.99 - it might not be cheap, but it can be done. I have a 40GB a month SIM (20GB doubled on a deal), and if I run out I can add more that way.