Mandatory OT, VL requests, Working hours

Hi,

I am new here and I have some questions about mandatory OT, VL requests and working hours.
1. Mandatory OT: our company director sent a message about mandatory OT as not against labor code since we signed a contract. Agents do not have the right to complaint since they sent out this memo. Is that really true? That we can't do anything about mandatory OT?
2. VL requests, according to our manager, vl requests are benefits and not a right. their reason is that, it needs to be approved first. Is that also true?
3. Working hours: we changed schedule and our shift was from 12am to 9am tuesday wednesday off then changed to 8pm to 5am with the same off (tue-wed) then the management team wants us to go to work on the same day (monday) at night at 8pm to 5am so we will be having 2 shifts for the said date. also they don't want us to punch in our schedule since the system will already be locked due to our earlier punch. then agents will be having post shift as well in the earlier schedule.

i would like to know if these are valid reasons to file a case in nlrc. Thanks!

you can file a complaint at the nearest dole office, but note,

ot can be required, but should not be permanent

vls are indeed discretionary

those changes suck, but imo, not a basis for a complaint