European nations have closed down over 50 Internet websites after a crackdown on mobile phone ringtone scams often targeting youngsters.
In an 18-month "consumer crackdown" 300 websites were investigated and most were not operating properly, the European Commission said in a statement.
A total of 159 websites were "corrected" while a further 54 were closed down completely.
The three main problems identified by investigators were unclear pricing, incomplete trader information and misleading advertising, in particular, advertising ringtones as "free" where the consumer is in fact tied into a paying subscription, the commission said.
Three quarters of all the websites checked lacked some of the information needed to contact the trader.
Over half of the websites involved specifically targeted children, many using favourite cartoon, or other television, characters.
"This EU-wide investigation was a direct response to hundreds of complaints coming in from parents and consumers from many different EU countries," said EU Consumer Commissioner Meglena Kuneva.
"Young people should not have to fall victim to scams like misleading advertising that lure them into ringtone subscriptions they thought were free. And parents should not find nasty surprises in their phone bill, when their children by accident have signed up to more than they have bargained for," she added.