Poor Service

I'm working for Teleperformance in Woodstock. Tonight I came from my shift at 18:28 and I was told that the driver left at 18:25. According to the our company the vehicles were supposed to leave at 18:30. Also one evening the driver leaves at 18:30, ehy all of a sudden do they leave at 18:25. I would like an explanation for this and that your employees should be on the same page