Maybe she should see an attorney. My sister worked at either Sears or JC Penny for twenty years. Later it was part time. A manager was working on getting rid of her. Then they cut her hours to like ten a month. Then one summer my sister had poison ivy, and she was scheduled to work while she had it. She called other employees and switched her hours with someone. Then that someone called her later and told her she couldn't switch her hours because she was old my sister didn't work there any more.
That was probably the purpose of putting in a new manager -to replace employees.