Forty-one of Google’s European online shopping rivals still say the Mountain View, California-based company isn’t playing fair.

A letter from companies in 21 European Union countries seen by Reuters asks European Competition Commissioner Margrethe Vestager to take action against Google for favoring its own price-comparison shopping service (CSS).   

Company executives who signed the letter are from Idealo, Europe’s price-comparison shopping service; Poland’s Ceneo; Britain’s Kelkoo; and Foundem and Heureka in the Czech Republic. Some are newcomers to the complaint, raising concerns for the first time, while others like Foundem’s founders Adam and Shivaun Raff lead the charge.

“They said Google’s proposal to allow competitors to bid for advertising space at the top of a search page had not boosted traffic to their sites,” reports Reuters.

Some marketers question whether or not that has anything to do with the respective companies’ search engine optimization and paid-advertising efforts.

Last year the EU fined Google about $2.65 billion for abusing its dominance as a search engine to promote the company’s own products in its online advertising service.

Hundreds of companies participate in the auction that allows comparison shopping sites to run product listing ads in Google Shopping results. While Google believes it has changed its guidelines to meet EU policies, the 41 companies argue that Google has not complied.  

Calling Google an “advertising broker,” Vestager in August spoke about platforms and competition, pointing specifically to the search engine’s dominance and how it “harmed competition and consumers.”