The Dutch consumers association Consumentenbond and homeowners’ lobby group VEH are pressing ahead with their collective claim against six major Dutch energy providers, accusing them of illegally increasing rates for people on variable contracts from 2017.

The case stems from another court ruling earlier this year concerning Vattenfall, which raised its variable rates in April 2022 in response to rapidly rising prices on the international gas markets. They had quadrupled between January and August.

In March, the appeal court in Amsterdam said Vattenfall’s decision to hike prices in April was an “unfair trading practice” because the conditions of its variable contract stated that rates would change twice a year, in January and July.

Essent, Eneco, Greenchoice, Energiedirect and Budget Thuis are also included in the claim, which could run from hundreds to thousands of euros per household depending on energy use and the term of the contract.

Talks with the energy firms failed to produce a result, and the organisations have now decided to press ahead through the courts.

“Our aim was to resolve this together. But unfortunately, the discussions—if they happened at all—led to nothing,” said VEH director Cindy Kremer. “This is extremely disappointing. That leaves us with no choice but to launch a collective action.”

The ruling has implications for all consumers with a variable contract, because almost all energy firms used the same conditions. And that, the Consumentenbond says, means millions of consumers have paid too much.

So far, 175,000 Consumentenbond members have signed up for the case, as have 50,000 homeowners via the VEH registration system.