My 派遣会社 made calculation errors on my payslips

To start with, i work at a factory on grave yard shifts, so even on my minimum wage, i get paid night differential. I recently received my payslip for this month which is previous month's work and i felt disappointed at how small it was despite it being on night differential. It was then that i started to carefully check my previous payslips that noticed that there are discrepancies… I don't know if they are miscaculations on the hakengaisha's part or some sort of modus? Because it didn't just occur once, but multiple times. They seem to make errors on counting my overtime hours and the hours with night differential. Regardless if it's just a few hours worth of salary, i can't lie it all matters to me because it does make a lot of difference given that i earn minimum. I just feel mad and disappointed because i know i worked my ass out for those few hours. I totally hate myself for not noticing sooner.

So, my question is… What can i possibly do? They have already released the gensen. On top of that i already worked for this factory (under a hakengaisha) for awhile and i am afraid i might jeooardize it by complaining. I can't afford to lose my job. I want to inquire and complain to the hakengaisha but i have been advised by someone to just wait it out until they make another miscalculation again.

Thank you in advance and i hope for understanding.

by quertybabe0000