Being paid apprenticeship with out aprenticeship

Hi,
My sister in law has been working at a copy shop type place since april or may and has been paid the apprenticeship wage because she was hired to work as an apprentice. She has been there now for months and never assigned her the instructor she needed for the actual apprenticeship. She had inquired about it numerous times and they kept saying they were working on it. All the while she was being paid apprenticeship wage. Now on september 19th they told her her time with them will end the 5th of october when she was under the impression she was going to be getting an instructor. So basically this whole time they did not give her the apprenticeship but she was paid the apprenticeship wage. Now she will be terminated and they are saying it is because they don't think she does well. So I am curious if this is illegal if she is owed the balance that she should have been paid for minimum wage? Also is there somewhere she can report this? Because according to other people who work with her in the office this employer does this often. Thank you for your time if there is any advice you can give me to let her know if there is something she can do cause this just doesnt seem fair or legal from my point of view but I'm from the US so I don't know the laws here.
Thank you