We have a number of employees who have contracts that say mon – fri 9am – 5pm with occasional weekend work.

The bulk of our staff have been with us well over 9 – years where the weekend work has never taken place.

Now all of a sudden we have scheduled a person to work in September on a Sunday.

Under custom and practice can we envoke working on a Sunday considering we have not asked for this in the last 9 years by our employees.?