I work as a project coordinator for a large healthcare company and dedicate my entire time to this one project. I used to do another one in addition when both projects were smaller, but I got moved to cover my main project as it had doubled in size and workload. There's another teammate that took over the smaller project in addition to her other duties, but whenever she took PTO I'd have to cover.
Now that my main project has tripled in size and workload (they're aware of this), they promised another teammate would be cross-trained to cover if the other gal went on PTO so I wouldn't have to. There have been two instances this year where I still had to cover and I told them “Every time I have to cover, I fall behind on my main project. I'm gonna take up a lot of overtime doing this” (which they hate giving).
The teammate who is supposed to cover is actually swamped with a ton of other tasks and was never even told she'd be crosstrained. In fact, they give her all these projects and have the audacity to say “it doesn't take that long”. With the other teammate going on PTO soon, I know they're going to have me cover. They don't even ask, they just say “(teammate) is out on PTO, thanks for covering!”
What's a good response I can prepare? I'd want to go along the lines of “I don't appreciate you giving empty promises that this project would be taken off my hands when you already know my main project requires my full attention”. FYI I do have quite the micromanager who couldn't be bothered to learn how to cover the job or hire more staff when people leave.