Meddling co-workers

So the person that had the late hours, 9:15am - 5:30pm, retired a couple of weeks ago leaving no clerk to do his job. Management was/is adamant about not re-posting his job for bidding so I offered to change my schedule and work his hours. My reasons for doing this were to get his days off, Sat/Sun, so it would be much easier for me to go racing.

So last week I started working these hours only to hear a couple of my co-workers complaining about it. Now before I took over the hours all of the clerks senior to me were given the chance to take these hours/days off and turned it down. So I start working them and suddenly I'm getting over time like crazy and they're complaining and then the union gets involved. I'll tell you this, I hate this stinking union!! They had no business getting involved here, the situation was handled, no rules broken, but no they have to step in and I get screwed for it.

So now I go back to my regular hours/days off thanks to two worthless co-workers whose petty actions have really pissed me off (that means no more nice guy to them and doing all the work).