I hate it when this happens! What do I do now?

I work hard to protect my 100% feedback rating. Today I recieved a negative from someone overseas who states they havent recieved their item. I have had no communication what so ever from this buyer. Just bang! Neg. feedback left. Is there anyway I can get ebay to remove it? The buyer has a feedback of 1  Yep! Also I state that delivery will take between 1-3 weeks and It is not 3 weeks yet, so realistically it still could arrive. I hate these situations.......