should a vet working for va pay higher health premiums

A vet working for the VA as part-time, but has worked 40 hours since day one pay more for health benefits, because they are officially scheduled fro SAT. and Sun., so it does not matter they work the same amount of hours as a full-time employee and just as hard. There are only two groups that work par-time for long periods of time and are held back from being full-time paying less for the same benefits. Our Union is weak and I don't know who to talk to about the unfairness of using part-time vets as full-time personnel and giving them the worst hours to work with very few personal, with higher cost for insurance premiums than a doctor or nurse when my pay is not as high as their's. The bad thing is I have 20 years in the military, 7 years federal time.