This is the only properly unlimited tariff I have seen.
It says £18 on the website but that excludes VAT
Also says subject to fair use but no numbers anywhere and you never pay more that the flat rate.
Vodafone also have the fastest network at 7.2Mbps and they are currently upgrading to 14.4Mbps
First post so please be nice
NOTE: Quidco is through 'Vodafone Business' NOT Vodafone
EDIT: Did some phoning around, turns out there is a 5GB allowance but all they do is cap your speed to 25% of what you usually get. Its still unlimited.
Also with 14.4Mbps connection you can actually expect between 2-4Mbps actual speed.