If you think management has violated the contract ask to see a union steward.
Then you want to write a statement on the situation. Do you have the Who? What? When? Where? Why? The date and the time frame are important to keep track of and to make sure that’s in your statement. When you’re done writing your statement print and sign your name with your Employee ID number and date that you wrote this statement. Then the Steward will investigate the possible grievance. It’s best to file close to the date that the situation occurred.