British Gas engineers are being balloted over possible strike action during the festive period as a row over contracts worsens.
Thousands of GMB union members will vote on industrial action which could see engineers not fixing British Gas customers’ broken-down boilers.
The elderly and vulnerable in homes without heating will be exempt.
British Gas-owner Centrica said the proposed changes to contracts were vital for its business.
The row between GMB and Centrica centres on proposed new terms and conditions, which include changes to holiday allowances and no extra overtime pay.
The union is angry about Centrica’s “threat” made in July to fire and rehire 20,000 workers should those changes not be accepted.
Workers would be fired and then rehired on the conditions regardless of whether they had accepted them or not, the union says. However, Centrica said such a move would be a last resort.
The union said that members’ anger was “boiling over”. “People don’t like threats and bullying and GMB members are no different.” said GMB national secretary Justin Bowden.
Union members were angry in August after the Centrica “ultimatum” on jobs, and 95% voted for action, he said.
“We sought to get the threat off the table. The best that they [Centrica] were prepared to do was postpone the ultimatum until January,” Mr Bowden added.
Centrica said that it had lost more than a million British Gas customers in the past two years to competitors with lower-priced products, and that it had lost more than half its earnings.
“To win back customers from our competitors and reverse the decline of our business we must have flexibility to give customers what they want, at a price they want and when they need it,” a Centrica spokesperson said.
“Our current terms and conditions are stopping us doing this and modernising the way we work is critical to our success,” the spokesperson added.
Base pay and pensions would be protected, the company said, and the contract changes would reduce its wage bill by 1.5%.