Whether she would get the information she is interested in, i.e. which account she is linked to, is another question.
Well if they don't provide it, they are breaking the law, so you can complain about them again that way.
If information is withheld she my be able to infer that the offending account to which she is linked is held by someone else - though the identity of the account holder would understandably not be given.
In any case, it sounds straight out of Kafka: you're punished, but you don't know what crime you are supposed to have committed.
That's quite an interesting legal tactic they've got going there!