Which? is warning that customers are being seriously misled by broadband providers' claims about the speed of their services.
It points to a loophole in advertising guidelines that allow providers to claim 'up to' speeds that apply to only 10% of connections. And, says Which?, only 12% of customers are aware of this rule.
"Internet connection is now an essential part of modern life so it beggars belief that providers can sell people short by advertising speeds that only 10% of customers could receive," says Which? executive director, Richard Lloyd.
"We want advertising watchdogs to pull the plug on confusing adverts and ensure broadband providers show the speeds the majority of customers will actually get."
Which is calling on advertising watchdogs the Committee of Advertising Practice (CAP) and the Broadcasting Committee of Advertising Practice (BCAP) to review their guidelines on speed claims made in broadband advertisements. Claims such as 'superfast' should be quantified, it says.
Any speeds advertised should be available to the majority of customers, not the minority, and providers should be upfront about how many people can actually get the speed advertised.
Various factors affect the speed a customer actually gets, from their distance from the telephone exchange to the number of local subscribers sharing the same network.
According to Ofcom, across the UK, the average speed for residential customers is 18.7Mbps - but an unlucky 3% of people get less than 2Mbps. The government says it intends to make sure that 95% of the population should be able to get 24Mbps by 2017.
According to Ofcom, Virgin Media's 'up to' 152Mbps cable service, which launched in February, gave the fastest download speed over a 24 hour period, averaging 141.9Mbps. This was followed by BT's 'up to' 76Mbps fibre package, which delivered an average speed of 62.0Mbpss.
"It's important for us to provide consumers with the best possible information to help them understand the options available to them when choosing broadband, how different packages perform, and what they can do to get the most from their services," says Ofcom chief executive Ed Richards.
Existing customers who suspect they're not getting the speeds they should can check on one of many speed checkers online - Which? has its own, here.
And if you're thinking of shifting to another provider - or if you're looking to move house - Rightmove has a tool allowing you to make a comparison. According to the company, one in five people now actively check internet speeds when looking at different areas, and one in 10 has walked away from a property because the broadband wasn't up to par.
Rightmove says its tool gives the speed that users in the area should expect to receive 75% of the time - although this doesn't necessarily mean it's what you'll get at a particular address.
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