Vodafone believes consumers could be forced to pay over the odds due to a delay in the introduction of lower superfast broadband prices.
Earlier this year, Ofcom called for the wholesale cost of 40Mbps superfast broadband to the likes of TalkTalk and Sky to come down from £88 a year to £52.77 a year.
Ofcom believes reducing wholesale costs would promote competition in the superfast broadband market, enabling companies to create their own full-fibre ultrafast networks to compete with Openreach.
This would in turn mean that consumers get the benefit of lower costs by next year.
However, the price reductions were delayed so the regulator could closely examine the findings of a review into the telecoms market.
Vodafone believes this means consumers will end up paying more than they would do otherwise in order to access a superfast connection, the Financial Times reports.
"We estimate that as a result of the 12-month delay in implementing this initial charge control and the subsequent delay in further reductions, UK consumers are being overcharged by around £140 million," the company said.
"This windfall gain will allow Openreach to invest in fibre-to-the-premise to cover a city the size of Cardiff or make a substantial contribution towards improving the quality of rural broadband."
TalkTalk agreed that the delay would lead to consumers paying an extra £140 million, while Sky said the cost of supplying superfast broadband to customers would be "higher than necessary".
"Competition will be further distorted and consumers harmed," the company warned.
Ofcom has promised that it will look at the claims and ensure BT continues to offer fair wholesale prices.
Openreach commented: "Ofcom is consulting on the new price control that should apply to our MPF product and the various responses show there’s no consensus yet on what the appropriate price should be.
"To avoid uncertainty from the current controls lapsing, we voluntarily committed to hold prices at 2015/16 levels to make sure CPs have pricing certainty.
"We believe the current price is fair and reasonable, which is our regulatory obligation and we’ll respond to Ofcom’s consultation and give our view on the future.
"The CPs of course argue prices should come down, and Ofcom needs to consider the evidence and reach an independent decision. That consultation is ongoing so it would be wrong for them to pre-empt the outcome now.”