Any person who is affected by or has witnessed or knowledge of any forms of abuses, exploitation or contract violation can report such incidents to the authorities, Embassy, employer or other support network. The immediate the reporting is, the better in order not to aggravate or prolong the situation. There are emergency hotline numbers especially if the situation demands immediate response from the police or hospital or for rescue. As such, memorise these emergency or hotline numbers, or keep a copy of these numbers which you can easily access.
In filing formal complaints, however, depending on the remedial laws or procedures of the country, only the victims or the affected party/person may file a case. The others may issue an affidavit either as witness or have personal knowledge of the incidents.