TalkTalk has called for a serious overhaul of Openreach, following the release of a damning report by MPs.
Earlier this week, the Culture, Media and Sport Committee said BT has significantly underinvested in its infrastructure subsidiary and offered a poor standard of service.
The group of MPs also stated that BT has exploited its position to make strategic decisions that favour its own priorities and interests.
BT was therefore warned that if it fails to offer the reforms and investment assurances necessary to satisfy its concerns, sector watchdog Ofcom should "move to enforce full separation of Openreach".
Responding to the report's findings, TalkTalk said the need for radical reform of Openreach is now "beyond doubt".
Dido Harding, Chief Executive of the company, commented: "MPs have concluded that Openreach is not fit for purpose and is letting Britain down.
"As Ofcom considers how to improve Britain’s broadband, it should feel emboldened to know it has cross-party political support to be radical."
Ms Harding went on to criticise BT for breaking its promises, saying it risks creating a two-tier digital Britain, with millions of homes and businesses being denied fast and reliable broadband.
"Britain needs an independent Openreach, freed from the shackles of BT and able to invest in world-class technology for the whole country, not just parts of it," she stated.
Ms Harding added that customers deserve nothing less after "years of suffering".
Openreach this week insisted that it has seen strong improvements in customer service performance.
For instance, it said Openreach engineers are fixing 84 per cent of faults inside two working days, compared with 67 per cent two years ago.
Openreach also stated that it is exceeding all of the 60 service measures set by Ofcom, as well as recruiting an additional 1,000 engineers this year and simplifying the way it works to achieve better outcomes.