The万能的推油, wife's sister, has been working for over half a year without social security, and her salary is paid via bank transfer. She's been on probation the entire time, only started clocking in October, and just signed a formal contract with three or four days ago.

Today, she asked in the office when she would receive the contract, and the supervisor told her she was immature, inappropriate in her conduct, and told her to admit fault and write a letter of guarantee. After she refused, they said her attitude was problematic, she was insubordinate, and asked her to submit a resignation application.

How can she protect her rights in this situation?