Cannot deliver on time

I ordered an item from the USA, and paid for priority shipping (1-3 days), for which I paid dearly. Fedex is already past the delivery date, and seem to be taking their time to clear the parcel with customs, despite me providing all info that they need. Fedex has the audacity to blame the delay on customs, telling me that it takes up to 5 days to clear a parcel with customs. I normally use UPS, Aramex or DHL (unfortunately in this case the merchant only offered Fedex as their shipping agent) The above couriers clear the parcels with customs while the parcel is in transit, and it takes mere hours, not days. Very unhappy with their service, and will make a point to never use them again in future.