I work part time for a company. There are 6 part-time workers. The boss assigned an added responsibility to the 6 of us and I told him I'm not doing it. I want to be full time, instead of just having more work dumped on me and being told to go above and beyond! They don't pay me enough!
Anyhow, the other 5 part time workers made up a schedule for this duty and put me on it-after I flat out told them I'm not doing it! I emailed them that they're not my supervisors and have no right to tell me what to do! I work hard. They emailed me how hard they work and that we were all assigned this duty! Then they went to HR! HR is on there side but I'm not doing it! I'm not being taken advantage of!
I'm with your coworkers. They were assigned the same duty and they accepted it gracefully, so they made a schedule to divvy up the work equally. If you don't do it, that means even more work for them. Why should you be exempt? I'd have gone to HR too.