How long a person detained using transit visa for overstaying?

My daugher was caught last nov.14,2017..an agent here in phils.recruit them to go to your place ..the gave them a busy a transit visa.i think they what the policy of using that kind of visa...when they arrived in china they gave to their employeer..sir/madam they all victims of illegal recruiter here.i would like to know how long they will be detained?