The Dutch consumers authority ACM has fined the big four telecom companies – KPN, Tele2, T-Mobile and Vodafone – a total of over €13m for displaying ‘incorrect and incomplete’ information on their consumer websites.

The lack of proper information means consumers are unable to make proper comparisons and chose what plan best suits their needs, the ACM said. In addition, the agency said, incorrect or incomplete information could lead to unfair competition.

The fines follow reports from consumers about ‘unexpected costs and hefty bills’ and come after telecom firms failed to take action despite a warning that the investigation would take place.

All four telecom firms failed to clearly present one-off costs, making deals look cheaper than it really is, the ACM said. Tele2 and T-Mobile stated that their deals included unlimited data, when this was not case within the EU and KPN offered voice and text message plans which were not unlimited, as claimed.

Vodafone was also fined for offering a plan at a price that only applied to existing Ziggo customers and which would cost €5 more for new clients.

The biggest fine, over €3.9m when to T-Mobile. KPN was fined almost €3.5m, Vodafone €3.1m and Tele2 €2.7m.