Unfortunately it's a fact of life that the baggage handlers don't always take the best care of our suitcases!  Our advice is ALWAYS to closely inspect your case when you recover it from the carousel for ANY DAMAGE that has appeared since you checked it in.  If something has happened notify your airline THERE AND THEN - you'll find that they have procedures in place to help you.  The airline has a duty of care in transporting you and your luggage and  it is THEIR RESPONSIBILTY to make good any damage that has occurred whilst your bags are in their custody. The warranty for your luggage specifically ONLY covers MANUFACTURING DEFECTS in the product and must not be relied on to make good damage caused by others.