BT’s share price fell on Monday after news that landline customers are bringing a £600m compensation claim for alleged overcharging.
The claims relate to a 2017 ruling by telecoms regulator Ofcom that people who only had a landline telephone were “getting poor value for money in a market that is not serving them well enough”.
Campaigners, led by Justin Le Patourel, the founder of Collective Action on Land Lines (Call), say that BT still has not compensated customers who overpaid.
Mr Le Patourel, who worked for the regulator for 13 years, said: “Ofcom made it very clear that BT had spent years overcharging landline customers but did not order it to repay the money it made from this.
“We think millions of BT’s most loyal landline customers could be entitled to compensation of up to £500 each, and the filing of this claim starts that process.”
BT said it “strongly disagreed” with the action and intends to “vigorously” defend itself, adding that it had offered discounted landline and broadband packages for years.
Natasha Pearman, of Mishcon de Reya, said: “This is a specialist claim that will be heard before the Competition Appeal Tribunal.
“It will take time to gather evidence and bring it to trial, but we are very confident that eventually millions of BT’s most loyal customers – many of whom are older and potentially vulnerable – will receive a significant rebate.”
BT said in a statement: “We strongly disagree with the claim being brought against us.
“We take our responsibilities to older and more vulnerable customers very seriously and will defend ourselves against any claim that suggests otherwise.
“For many years, we’ve offered discounted landline and broadband packages in what is a competitive market, and take pride in our work with elderly and vulnerable groups, as well as our work on the customer fairness agenda.
Rocio Concha, director of policy and advocacy at consumer group Which?, said: “Which? has campaigned long and hard for an effective collective redress scheme, but with no claim under the new regime reaching a full trial, consumers have not yet had the results they need.
“If successful, this opt-out action would be welcomed by many BT customers who were found to have been historically overcharged for years, but saw no refund as a result.”