Checkers treating staff like slaves with no pay

I am appalled by the service checkers provides to their internal customers namely thier staff. my sibling worked from 8am till 8pm 29 February at Checkers Westgate Mall. I understand they need to clean and pack the items back, they had i would say 5 customers in the store till 8:30pm. They however let the front end staff work till 9:45pm. I spoke to the Front end floor supervisors Kayyaam and the later Nozuko. they advised the people will leave when the store is clean. The work as cashiers and till packers and are expected to ensure the store is clean, some of these people like my sibling has been working her shift since 8am yesterday and at 9:20pm he advises they still need to clean and will be paid overtime, I know for a fact they do not pay these people overtime they only get paid for their shifted hours. Labour law advised that 12 hours between your shift and if you already working a 12hour shift how can they expect you to stay after your shift for almost 2 hours without exaggerating WITHOUT PAY!!! They also have family and transport that needs to pick them up. Waiting 30 minutes after 8pm is okay but having to wait till 9:45pm for a person who's shift ended at 8pm is ********.