No, the regulator did not decide to complain: the regulator decided to investigate and made perfectly clear in their announcement that they have not reached any conclusions yet. You are confusing the start of an investigation with a notice of regulatory violation.
If your neighbor goes to the police and claims that your assaulted him, the police is going to start an investigation. It doesn't mean they established already that you are guilty or even that a crime has actually been committed: they are simply acting upon whatever information they have been provided and try to establish whether the information is credible, what happened, whether what happened is illegal and if it seems illegal who is likely to be the culprit.
This is likely exactly the same situation: some company likely filed a complaint to the regulator and the regulator started an investigation to figure out the merits of the complaint and potential violations.
What would you have them do exactly? Ignore a complaint without investigating its merits?