Over 15 million UK households are not receiving the maximum broadband speed they are paying for.

Compounding the issue, just 17% of households are able to achieve the average advertised speed, according to a survey conducted by consumer watchdog Which?. It found that broadband speeds were worst in rural areas, where 98% of households were unable to get the maximum speed advertised by broadband providers.

Companies like Sky, Virgin, BT and TalkTalk advertise their broadband services as having downloads speed of "up to" a certain amount of megabits per second (Mbps). The average or lowest speed is not advertised, nor is the likelihood of a household being able to achieve the maximum speed. Under current rules, broadband providers must ensure that 10% of customers can achieve the maximum speeds advertised.

The report found that only Virgin Media met this target. Which? said: "In our analysis, the cable-provider Virgin Media is the only company that delivered the advertised speed to the majority (98%) of their customers. With each of their packages, at least 96% of customers received the maximum advertised speed."

Ofcom, the telecoms regulator, has started a crackdown on broadband speeds and customer service, making it easier for customers to ditch their provider if download speeds are lower than expected. But Which? says more needs to be done, with three quarters of households unable to get the maximum speed they're paying for.

Not good enough

"We want Ofcom to ensure consumers get the speeds promised by providers," Which? executive director Richard Lloyd told the BBC. "It is not good enough that millions of homes are so poorly served by their broadband provider with speeds that just don't live up to what was advertised."

Which? research found that just 4% of TalkTalk customers paying for a 17Mbps package were getting that speed, and just 1% of BT's 76Mbps customers were getting what they paid for. TalKTalk defended this claim, stating the company is "compliant with the advertising guidelines and if they change, we will continue to comply."

BT also defended itself against Which?'s findings, claiming over 10% of its customers signed up to the top package achieve speeds of 80Mbps or more. "We're very clear that customers should not rely on headline claims, but instead use the personal speed quote we give them at the point of sale, which is based on their own line," BT said in a statement.

A household's broadband speeds depends on the quality and age of the cables providing the service, and how far away they are from the local telephone exchange.

Tom Mockridge, Virgin Media CEO, said: "It's time to raise the bar: customers who sign up for superfast broadband shouldn't be stuck in the slow lane. Outdated advertising rules allowing providers to claim superfast speeds only available to 10 per cent of customers need to change. Advertised speeds should be available to the many not the few."