You can read more about the situation here. But to sum it up, a Cambridge University researcher developed a Facebook app that contained a personality test and though 270,000 took the test, Facebook's policies allowed the app to also collect data on many of those test-takers' Facebook friends as well. In all, the app collected Facebook profile information on around 50 million users and the researcher then handed that data over to Cambridge Analytica -- a political data analytics firm funded by the likes of billionaire Robert Mercer that aimed to use such data to better target ads and content to specific individuals. The company has been accused of using its methods during the US presidential election and the Brexit campaign.

In his letter, Collins says that Facebook's representatives have repeatedly understated the risks that go along with the way companies can acquire and hold on to Facebook user data. "It is now time to hear from a senior Facebook executive with the sufficient authority to give an accurate account of this catastrophic failure of process," writes Collins. "There is a strong public interest test regarding user protection. Accordingly we are sure you will understand the need for a representative from right at the top of the organisation to address concerns. Given your commitment at the start of the New Year to 'fixing' Facebook, I hope that this representative will be you."

US Senator Ron Wyden also sent Zuckerberg a letter asking for more information about the situation. And the FTC is now investigating Facebook's use of personal data.

Collins has asked for a response from Zuckerberg -- who has been rather quiet as these reports have been published -- by March 26th.