themailbro -
Since you work at Ground and are probably part time and need whatever wage / hours you can get, just clock in, since Saturday is your scheduled day. I was told many years ago that at Ground you were eligible for benefits after 1000 hours, which is about a year part time. Get all the hours you can if you want or need them. If they call / leave a message, do as others have said, ignore it and show up anyway. If they want to send you home ask for anything to do in the building or ask your manager for a sit down about your future at FedEx.