shorted on my paycheck, who do i talk to?

on tuesday the 3rd of may i was scheduled a full 8 hour shift.

as part of my job requirements, i cant leave until my replacement shows up.

my replacement was a full half hour late, so i should of had some OT pay listed on the stub for that period, i dont.

i'm fairly certain i also got shorted a half hour the next day, at just regular rate. and i've probably been shorted numerous other times when my replacement was late and i was here longer then scheduled.

i KNOW i got wrongfully shorted this time. i KNOW the GM makes a habit of adjusting clocked in times to match the written schedule (and the clocked in time is wrong, he cant be bothered to adjust that clock properly for some reason).

so the question is, who do i talk to about this, who is the proper authority i need to get involved?

EDD, the employment services place you go t for unemployment and job hunting assistance would be my guess. and they have an office only about 15 minutes away, and i do have weekday afternoons i can use to go see them.

am i correct in thinking EDD is the place to start?

BTW, this is in california, santa clara county.