Remember the $2.7 billion fine the European Union imposed on Google in 2017, for unfairly promoting its price comparison service, Google Shopping, over competitors' sites? According to a large group of Shopping rivals in the EU, the fine didn't do the trick, as Google still hasn't learned its lesson.

A group of 41 price comparison sites, including Idealo, Kelkoo, Ceneo and Foundem, have signed a joint letter to European Competition Commissioner Margrethe Vestager, accusing Google of "artfully avoiding compliance with the law," Reuters reported Thursday.

The EC ruling in June 2017 ordered Google to stop its competitive practices. "Google abused its market dominance as a search engine by promoting its own comparison shopping service in its search results, and demoting those of competitors," Vestager said at the time.

Google's solution for the issue was to allow competitors to bid for ad space on top of its search pages. But despite the company's claims that this has boosted the rivals' traffic, the group undersigning the letter says this hasn't happened, forcing "more and more" comparison shopping services to exit the market.

The letter, which was not made public but was seen by Reuters, does not offer a specific solution for the issue.

The European Commission confirmed to Reuters it had received the letter and said it was monitoring the situation. It's worth noting that Vestager recently commented on the issue, saying Google's solution isn't working.

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The EC also hit Google with a $5 billion fine in July 2018 for abusing its position in the smartphone market to increase the dominance of its search engine, as well as a $1.7 billion fine in March 2019 for abusive practices in online advertising to increase the dominant market position of its Adsense program.