Pretending to be Broker's Agent!

I was offered an investment plan by an agent. Who told me that if i invested $200, within 12 hours he will give me a return of $3500. I was convinced because i trusted the Broker because i've been using it for awhile and there's no issue for me. After i invested, the agent asked me to pay 15% fee of profits. He claimed it was Fund Manager's trading fee and Service Tax. Now the agent blocked me already. Please be aware if there's any agent pretending to work for the Broker and offers investment service, please stay away!