So to give some context, colleague and i work day and night shift withing a 24/7 environment. He does 12 hours and i do the other 12. He does day, i do night. Recently for the past 3 consecutive days he has been on average 20 minutes late to relieve me. What's upsetting is the fact that he doesnt message me indicating such after we had numerous discussions about this. He doesnt even apoligize for being late. It's making me sick. What should i do?