There is a huge gap between advertised broadband speeds and the actual speeds users can achieve, research has shown.
A survey by consumer group Which? found that broadband packages promising speeds of up to 8Mbps (megabits per second) actually achieved far less.
Tests of 300 customers' net connections revealed that the average download speed they were getting was 2.7Mbps.
Which? has called on regulator Ofcom and Trading Standards to launch a fresh investigation into UK broadband.
The speed tests were prompted by complaints from members of the public, unhappy with the speeds of their broadband connections.
In the last 12 months more internet service providers (ISPs) have offered services, promising speeds of up to 8Mbps.
The Advertising Standards Agency (ASA) has investigated several cases of misleading promotions, most recently asking Bulldog to make it clear in its adverts that speed was dependent on how far away from the exchange people lived.
It ruled that broadband providers could use the words "up to" 8Mbps when describing services as long as customers were likely to get close to those speeds.
The average speed achieved in the Which? trials was 2.7Mbps, with the lowest coming in at under 0.09Mbps, barely at dial-up rates, and the maximum only reaching 6.7Mbps.
"It is shocking that internet service providers can advertise ever-increasing speeds that seem to bear little resemblance to what most people can achieve in reality," said which.co.uk editor Malcolm Coles.
"If it's unlikely that you'll reach the advertised speed it should be made clear up front, so that you know with some certainty what you're buying," he added.
Lack of demand?
Ofcom told the BBC News website that it was monitoring the situation.
"If we get increasing complaints we may look at what more can be done. We are working closely with the ASA and it is very important that consumers know what they are getting and what they are paying for," said an Ofcom spokeswoman.
According to a Which? survey, done in conjunction with the speed tests, only one in 10 of its members thought that a broadband service advertised as up to 8Mbps would actually deliver the top speed.
Tim Johnson from analyst firm Point Topic believes that people are generally resigned to the fact that they are not going to get super-fast broadband any time soon.
"There is currently small demand for 8Mbps and we are in the early days for things that need that kind of bandwidth. The fact is that video generally is not served at those speeds even if you could receive it," he said.
A BT spokesman confirmed that 8Mbps would be a rarity for users.
"Virtually no-one will get it. The laws of physics start applying as soon as it leaves the exchange and you would have to live on top of the exchange to get the full 8 megabits," he said.
BT is currently upgrading its exchanges as part of its 21st Century Network (21CN) programme. It will allow for broadband speeds of up to 24Mbps and will start to be made available from early 2008.