yes i saw martin lewis (moneysaving expert) the other day saying o2 were the cheapest.
still don't forget to include your line rental
part of o2's fair usage policy
"But if you’re using the service excessively – like continually downloading large files at peak times – then we do reserve the right to warn you to lower your usage. In exceptional circumstances, we can even terminate your account.
This is because excessive use by a few people can reduce the speed that other customers in the same area can get. We just want to provide everyone with an excellent level of service."
well i don't know if they do cap you. but for the price, you cant complain..