Issuing Written Warnings for Mandatory OT in BPO

Hi, Im a supervisor in a call center. Our agents are being required to render overtime with pay. I understand that under section 10: (e) When the completion or continuation of work started before the 8th hour is necessary to prevent serious obstruction or prejudice to the business or operations of the employer; this can be an exception to require agents to render OT provided they are paid. My question is, if Im a supervisor and they are requiring us to render OT without pay and upon not rendering/reporting on said rest day OT they will issue a written warning, is this allowed by the law? Is there any section in labor code/code of ethics regarding issuing written warnings for not reporting on overtime when youre not even paid? Please advise so we would know if this is a case that we can raise at the nearest DOLE office. thank you!

OT has to be paid. i recommend you make a written inquiry with the management to question the practice.