Fraud job offer in bank

I called to a number who are providing job in private bank at Kolkata.The person told after conformation of the job 300/- have to be given.I went there and they give me a form to fill up and told after that 2500/- have to be given for mediclaim.They called me on 15th June 2016 and I have to pay on that day.I know they are fraud.But I want to catch them with proof.I will go on that day and do record the conversations.Kindly tell me ,to whom I can call to arrest them for fraud job offer consumer forum or police.