Microsoft faces more legal action in the UK, this time from a barrister named Alexander Wolfson who issued an opt-out class action claim this week alleging that public or private organizations in the UK that purchased certain software licenses (including for Microsoft Office and Windows) since October 1, 2015, were overcharged due to Microsoft’s market practices.

Wolfson, who retained the services of Stewarts LLP, a litigation-only law firm, said in a release issued on Wednesday, “Microsoft’s actions have had a significant and far-reaching impact on UK consumers, businesses, and public bodies.”

This claim, he said, “seeks to hold Microsoft to account and to secure compensation for the many affected members of the class. With billions of pounds potentially at stake, this case is about ensuring fairness in the digital marketplace and ensuring even the largest tech companies play by the rules.”