At the start of the year, Facebook and eBay committed to eliminate the blight of fake and misleading reviews on their sites after the Competition and Markets Authority (CMA) stepped in.

The CMA said millions of people base their shopping decisions on reviews, and if these are misleading or untrue, then shoppers could end up being duped into buying something that isn’t right for them.

But months after committing to introduce more robust systems to detect and remove such content, an investigation by consumer champion, Which? suggested Facebook is failing to uphold its agreement with the regulator.

It found dozens of groups with hundreds of thousands of members flooded the online platform with posts from users often described as ‘agents’, aiming to boost products on Amazon. They offer refunds, a commission or free products in exchange for users posting reviews, some specifically requesting five-star ratings.

A search for ‘Amazon review’ on Facebook revealed 16 of the top 25 groups were trading in reviews, with more than 200,000 members between them. One group had more than 36,000 members, while several groups boasted more than 20,000.

In one group there were 27,000 members and as many as 6,406 posts in a day, while across the groups there were at least 82,000 posts over a month.

Which? said it appeared activity had returned to levels it saw in research conducted last year.

In both investigations the average number of posts in individual groups over the 30 day period was between 5,100 and 5,600, suggesting either Facebook’s action is “not working” or “it is simply not taking any meaningful action”.

In one Facebook group Which? found an Enacfire Bluetooth speaker listed with the promise of a refund after review. On Amazon Marketplace, the same product – which wasn’t being sold directly by Enacfire – had a massive 2,558 ratings and a customer score of 4.9 out of 5. It was also appearing as the top result on a search for ‘Bluetooth speakers’, which had returned over 30,000 listings – leaving consumers at huge risk of being duped into buying a product boosted by incentivised, glowing feedback, Which? said.

Which? also found incentives being offered in exchange for positive reviews on two pieces of camping equipment, a Backture inflatable camping mat and a Backture inflatable lounger, which both also had the coveted Amazon’s Choice label. This indicates that the artificial five-star reviews obtained through Facebook fake review groups could have helped those pushing the products to not only boost the items up the rankings but also game their way to Amazon’s recommendation badge, which many consumers trust as a mark of quality.

When it came to eBay, Which? said it had taken a “proactive approach to stopping fake review listings appearing on its platform”, honouring its pledge to the regulator by dealing with the problem.

Which? believes Facebook must now show it is taking the problem seriously and demonstrate what more it will do to meet its commitment to the regulator. The CMA must also ensure it is closely monitoring Facebook, setting out its next steps if the site fails to crack down on the problem on its platform.

Natalie Hitchins, head of home products and services at Which?, said: “Our research shows that review trading groups continue to thrive on Facebook, leaving online shoppers at huge risk of being duped into buying products on Amazon that have been boosted by fake reviews.

“It’s clear that Facebook has not lived up to its commitment to the CMA and must urgently address the spate of fake review groups on its site, or the regulator must intervene again.

“The failure of sites like Facebook to crack down on bad practice underlines the need for online platforms to have more responsibility for content and activity on their sites.”

What do Facebook and Amazon say?

During the course of Which?’s investigation, Facebook had removed five groups. When Which? reported its findings to Facebook, it removed the remaining 11 groups.

A Facebook spokesperson, said: “Fraudulent activity is not allowed on our platforms, including offering or trading fake reviews. We have investigated and removed the groups brought to our attention, some of which were removed prior to Which? notifying us. We will continue to invest in technology and our safety and security teams to proactively prevent this kind of activity.”

An Amazon spokesperson, said: “We want Amazon customers to shop with confidence knowing that the reviews they read are authentic and relevant. We have clear policies for both reviewers and selling partners that prohibit abuse of our community features, and we suspend, ban, and take legal action against those who violate these policies.

“Our objective is to ensure customers see authentic and relevant reviews so they can make better informed purchasing decisions. To do this, we use powerful machine learning tools and skilled investigators to analyse over 10MM review submissions weekly, aiming to stop abusive reviews before they are ever published. In addition, we continue to monitor all existing reviews for signs of abuse and quickly take action if we find an issue.

“We are relentless in our efforts to protect the integrity of customer reviews, and we will continue to innovate to ensure customers can trust that every review on Amazon is authentic and relevant.”