Passport taken away

Hallo!
I have been to Thailand for 4 times and now coming for 5th time. Last time I found a girlfriend who I talk every day using line id video calls. I have an idea to take her with me this time or in the future. She works in massage. The problem is that her former employer from a massage parlour took her passport and did not give it back saying she did not do a good job. She worked there quite a short time. Employer asks 20,000 bht for giving back her passport. Can you advise me what is wise to do in the situation? Can police help? Or how to solve the problem?
Tnx for every answer,
Martin

This sounds more fishy that a fish shop after a heavy shower of fish on a Friday night in Galilee with some dude feeding 5,000 people a fish dinner.

Why would it matter if he took her passport? She'd just call the cops and get it back or go to immigration to report it stolen, get it cancelled and replace it.
Does she want you to lend her the cash?

Tnx! It gets more clare when I get there :)

I asked my Thai GF what she thought about your situation and she says not going to happen.  Employers might make copy of their Thai ID card but never ask if you have a passport.

Perhaps lady is not Thai if employer does have her passport.  I think it would be illegal for employer to keep that document and not return.

Tnx! Yes, lady is not Thai, but from a neighbouring country.

Seiklusreis

This is common practice when the girl working in a bar or massage is not only pouring drinks or giving a massage, also many places supply them with accommodation, well if you can call it that its usually a room with 3 other girls and they pay it from their wages. I have a few friends who have been in that position and the serious ones simply pay it, not fair but thats Thailand

go to the tourist police first to ask their advice mate.
The girls employer has no legal right to take her passport and refuse to give it back to her.