Anyone who leaves work without pay because their partner fails to show up is an idiot. Anyone who is scheduled for 12 hours, and is sent home without pay and accepts this due to a scheduling issue is an even bigger idiot.
If you are scheduled for 12 hours, I'm pretty sure they are required by law to pay you for 12 hours.
If we have a call out, we will attempt to contact all per diem employees and see if they want to come in and work. If we have multiple call outs, overtime may be authorized by upper management.
If MY partner doesn't show up, and there is no scheduled staff, then I stay for the duration of my shift. if the boss wants to put me as a 3rd on another truck, or have a supervisor hop on the truck, that's their choice. but I am scheduled for 12 hours, I will be at my post for 12 hours, and expect to be paid for 12 hours.
and if they have nothing for me to do, I will stare at the walls for 12 hours, at my salary rate. but I planned on spending 12 hours of my day at work, and I expect to be compensated for my time, regardless of it there is a scheduling problem that is not my fault. If I chose to leave after a certain amount of time (after being permitted to by my supervisor), that is one thing, but I planned on being at work for 12 hours, and that's where I am going to be.