She and her friends are being illegally screwed out of a quarter hour's pay.
She and her friends should all file a group wage complaint with the state. All of them doing it will provide some protection against retaliation. If only one does it, one is likely to be out of a job. Not right away, but after enough time has passed so that there will be no proof that it's related.
Shady employers know how to be shady when somebody turns them in.

