Consumer group Which? has called on regulators to clamp down on the way broadband firms advertise their connection speeds to customers.
It says that the rule makers need to impose tighter guidelines as companies are promising 'up to' speeds which are guaranteed for just 10% of customers.
As it stands, the rules stipulate that if just 10% of potential customers can get the maximum speed that broadband providers are advertising, then they are allowed to advertise it as such.
However, the consumer watchdog says that only 12% of customers are aware of this rule and Which? says that advertisements should match the experience of the majority of customers, rather than just a tenth.
"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," said 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.
"In the meantime, companies need to be more up-front with customers about the speeds they can expect."
Research from Which? shows that 88% of consumers value broadband speed as the second most important factor when considering which provider to go with, with 94% saying that price is key.
Nine out of 10 consumers agreed that internet speeds should be shown in advertisements.