Police not taking action on the FIR what to do

Sir, I have submitted a petition to the District Police Officer ( Superintend of Police ) Kannur on 14.6.2016 against certain persons who have cheated me through internet by offering a job visa to my son and collected huge amount, and later not providing the visa nor return the amount. I have deposited the amount to their account as directed by them. Since it was a cyber crime the DPO, Kannur forwarded my petition to the Station House Officer with a direction to investigate the crime. The Circle Inspector charged the case u/s 66D of IT Act 2000 and IPC section 420 and prepared the FIR after taking evidence from me and my son on 11.7.2016. It is understood that the Investigation Officer has collected the details of the Account Holder. But due to reasons unknown to me no further steps have been taken by the police to take the culprit under custody and file a charge sheet. I have approached the Investigating Officer many times he is showing laxity on his part.