Descrimination: A full hot meal or soup and a sandwich

Thank you for the feedback thus far. However, I think that there's some clarification that needs to be done.
1) Our collective aggreement states "The parties hereto agree that in every instance the employee shall pay a fair price for any meals obtained which shall in no intance be less than the actual cost of furnishing such meals, and the said cost shall be computed by the Corporation. When employees bring their own meal, they shall use the designated dining area for the consumption of same." In other words all employees are entitled to purchase a meal.
2) Up until the the first week of December, every employee in the building was entitled to purchase a full hot meal of what ever was being served to the residents that particular day. Every employee was treated equally. The only difference was that there was different meal times.
3) After the first week of December the employer singled out two categories of workers and said that they were not allowed to purchase a full hot meal like everyone else.
4) If the employer would have allowed the Practical Nurses and Care Aides to change their break times to eat their lunch after 12:30 pm like everyone else then there would be no arguement. Then everyone would once again still be treated equally and all entitled to purchase a full hot meal.
As it stands now the Practical Nurses and the Care Aides are not treated equally, thus the filing of the grievence.