Kolkata Foreign Lcao — tracking status of rf[protected]sg, retention reason : retained by customs for unspecified reason

Address:

Kolkata, West Bengal, 700001

I want to know the actual reason for retention of my parcel of tracking number rf[protected]sg because some tracking site shows custom clearance complete and some shows in progress and others shows held by customs... Please guide me what should i do to get my parcel soon.