LONDON—Facebook’s WhatsApp faces a complaint from European Union consumer groups who say the chat service has been unfairly pressuring users to accept a new privacy update in what it calls a breach of the bloc’s regulations. The European Consumer Organisation, or BEUC, filed a complaint Monday over the way WhatsApp has brought in changes to its terms of service and privacy policy, saying they aren’t transparent or easily understood by users. Many WhatsApp users switched to other chat apps like Signal and Telegram because of privacy concerns when the update was rolled out earlier this year because of concerns the changes would give Facebook access to more information on users. “WhatsApp has been bombarding users for months with aggressive and persistent pop-up messages to force them to accept its new terms of use and privacy policy,” BEUC Director General Monique Goyens said. “They’ve been telling users that their access to …