Late clearance of international parcles

My international has been with them since 20/10/2017 and they still haven't cleared it.I've sent them emails but they don't respond.When I call them the line is forever busy and when I finally get through I'm told that they have a backlog so they don't know when my parcel will be processed.How long does it take to clear an international parcel? Clearely it cant take a month...