Which Agency?
Who sent you, i.e. which Agency?
Maybe you can Post what they wrote exactly so we see the kind of wording they are deceiving us all?
Did you sign an pre-Agreement or similar?
Were you successful at the Selection?
If yes, did you decline the offer?
What do you have in writing from the Agent regarding re-imbursement; when, where, how much, how fast?
Most likely you were so excited about the Interview and possible job placement that you ignored/forgot to check the fine-print or get all the facts. Thus your unfortunate situation now which is not a one-timer.
Good luck. PM if you need help from us.