Facebook Inc. officials will be traveling -- or at least making phone calls -- to Europe to respond to concerns that the data of as many as 2.7 million people in the European Union might have been shared with a consulting firm that worked on Donald Trump’s U.S. presidential campaign.

Facebook (FB.O) Chief Operating Officer Sheryl Sandberg is planing a call with the EU’s justice commissioner, while the company’s top technology officer is expected to appear before a U.K. parliament committee and its deputy privacy chief will head to Italy.

The company has been refining its response in the wake of revelations that data on as many as 87 million people, most of them in the U.S., may have been improperly shared with research firm Cambridge Analytica. Chief Executive Officer Mark Zuckerberg, who will testify at U.S. congressional hearing next week, has changed tack by communicating directly with the press in interviews, and a group conference call late on Wednesday.

“It seems that with Facebook things got a bit out of hand, now the situation needs to be handled,” EU Justice Commissioner Vera Jourova said in a tweet Friday. “I do not want to see people being manipulated in a direction which is unknown to them, by unknown people who pay for it.”

Sandberg in an interview on Thursday at Facebook’s headquarters in Menlo Park, California, for the first time said that some advertisers have curtailed spending and acknowledging her team has a long way to go to reassure wary customers. She also sent a letter late Thursday to the EU trying to explain the steps Facebook has taken to protect data.

The response given isn’t enough yet for the EU, Jourova’s spokesman Christian Wigand told reporters in Brussels on Friday, saying that while the bloc’s executive agency still has to study the letter, “it is already clear that this will need further follow up discussions with Facebook.”

Sandberg and Jourova are scheduled to have a phone call early next week, Wigand said. EU data protection regulators from around the 28-nation bloc will also be meeting in Brussels next Tuesday and Wednesday to discuss their investigations, on which the U.K. watchdog has taken the lead.

The U.K.’s Information Commissioner’s Office in a statement on Thursday said that Facebook has been cooperating with regulators and that “it is too early to say” whether the policy changes Facebook is making “are sufficient.”

Other EU privacy regulators also weighed in on the data scandal, with Italian authorities saying on Thursday that they will meet with Stephen Deadman, Facebook’s deputy chief global privacy officer, on Apr. 24, as part of their investigation into the scandal.

A U.K. parliament committee investigating the impact of social media on recent elections on Friday announced former Cambridge Analytica CEO Alexander Nix and former director Brittany Kaiser as future witnesses for a Fake News inquiry. It said that Facebook Chief Technology Officer Mike Schroepfer had also been called as a witness.