Internet users are calling out a dozen tech giants for their sudden turnaround on a controversial privacy bill, launching an email campaign this week with the plain message, “You betrayed us.”

The chief executive officers of Apple, Microsoft, Adobe, IBM, Symantec, and other companies, along with Salesforce web hosting service, quietly sent a letter (pdf) to U.S. Congress earlier this month endorsing the Cybersecurity Information Sharing Act (CISA), a bill that would allow tech companies to share user information with the government in cases of “cybersecurity threats”—which privacy advocates say only serves to broaden government spying powers and reduce consumer protections.

Online activists say the reason the companies changed their stance on CISA—also known as the Cyber Threat Information Sharing Legislation, as it is referred to in the letter—is because the bill would grant them “total immunity” from prosecution for sharing private user data with the government.

“[T]hese companies know that their customers hate CISA, and so they’re jumping into the water together, hoping there’s safety in numbers,” the new campaign states at its website, YouBetrayedUs.org. “After all, you can’t blame Microsoft if Apple is doing the same thing, right?”

More than 15,000 users sent emails to the tech companies reading, “By supporting CISA, you are selling out your customers’ privacy to a power-obsessed government. And what are they giving you in return? Immunity from privacy laws will be nothing compared to the damage done to your businesses when consumers leave you.”