I work at a milk plant and today my coworker left early on me. He's always leaving me with tons of work to do!
Oh I bet that is frustrating!  Can you report it to someone?
I have a team leader who I can try to report it to but he always seems to brush me off. It's getting old at this point!
I would feel the same way.  Perhaps you could mention it to your co-worker nicely and they will take pity on you.  