Our hub has had trouble with staffing, so several of us have been double shifting most of the year. Eventually they told us you can work 6 days but not 7 days a week. We kind of just put up with it because we are happy to have the extra hours as part time. They could probably just work their staff a little longer but they want to run the sort less obviously so we both benefit. Now that peak is coming, or pretty much here, its worth hashing out. All double shifting should go by seniority. No one can triple shift, but as long as its not more than 2 shifts a day, you can work 7 days. Or that is the way it always has been in the past. My sort had a girl double shift this week and she got her 6th day, and her shift works Saturday which is 7. I showed up to work their shift. They had a need, they had double shifters. They told me I couldn't work because of the 7th day. I plan on filing seniority. The contract hasn't changed for over a year. Management is saying,"call the union. they will confirm it." This can't be true.