Virgin Media customers in some areas are receiving broadband speeds that are lower than the supplier promised, an investigation has found.
BBC's Watchdog revealed that an increase in Virgin Media's customer base meant that download speed in some parts of the country had fallen - in some cases to a fraction of those advertised.
Responding to the report, Virgin Media's Chief Executive Tom Mockridge said the issues raised by customers have been resolved, and further training has been put in place.
"All of our sales agents have been re-briefed on the company's sales policy," he explained. Virgin said it is "disappointed" to have fallen short of the standards it sets itself when it comes to delivering fast broadband.
In May of this year, Mr Mockridge said speeds of 100Mbps would be the "broadband standard" for Virgin Media.
Broadband expert for uSwitch.com Ewan Taylor-Gibson said the issues highlighted the need for customers to "feel they are receiving the service they have signed up to".
"Issues like this can arise when the expectations set by providers fail to meet the expectations of the customer," he explained.
At present, only ten per cent of customers need to receive the speed mentioned when advertising broadband packages for the provider to claim it as an 'up-to' speed.
Mr Taylor-Gibson said the real information customers need is the "estimated average and minimum speed they can expect each provider to deliver to their property", adding that this information needs to be made clearly available during the sales process".
He also noted consumers should be able to exit their contracts without penalty if they do not receive the broadband speeds providers have pledged to deliver.