Unable to withdraw part 1

This trading platform is really quick on depositing, but it keep delaying for withdrawal for various reasons(tax, handling fee, margin, late fee, Expedited charges, etc) and keep requiring to deposit. After all the payments were made, they say that the deposit was suspected of money laundering and they need to cooperate with bank for investigation. If the money transferred from this platform is suspected of money laundering, it this the problem of investors or the platform itself? Also, this platform promise to compensate the loss of customer. How long does it take for bank to investigate the source of funds? The original netizens have disappeared and they are completely ignored me. How can I ask for assistance in getting the defrauded funds back?