corrections and forced overtime

[Anonymous <no_email@fake.address>]

Retaliation by forcing Overtime work.  Our workplace is always short of staff.  Management does not hire enough good workers.  As a result of this, the work schedule is a mess.  It is their responsibility as supervisors to maintain the schedule.  There are open slots on the schedule that must be covered, and they leave us 
notes, call "so and so" and have them work this/these shifts.  I was recently on a break, for 4 days, and had been asked if I could work several shifts.  I stated, "NO,
I will be out of town."  The entire time I was gone, the phone rang constantly, with requests to know when I would
be back so I could work.  
I had resigned my status as being "Officer In Charge" of
the work shift.  I was then asked if I would resume this
position.  I replied in writing, that I did not and would not take the position back.  I feel, in retaliation, the
supervisors have jammed overtime on to me and another worker, who is in the same position.  Other people had volunteered to work the shifts, yet it is 'ordered' by our
supervisors/bosses that we must work these shifts.  
I am just totally disgusted by such tactics, the result of poor management, and a 'get even' mentality in the work place.  We have no recourse, we are 'public servants' who
seem stuck at the mercy of supervisors.  Any suggestions, 
please??!!!!!