Norwegian Air Shuttle — lost luggage and no customer support

First time I fly with Norwegian. We purchased Premium tickets. Good service on board, but they lost both our luggage and we are chasing the airline from US and Italy to find out location of suitcases. In US they do not answer the phone, in Italy they say to wait and they do not know if luggage is in Italy or US. They do not reply to emails, absolutely dreadful customer service, no support at all. They are spoiling our vacation.