Unwanted present from my neighbor

Some background info: Defector and I stays on the 13th level of our block, there's 3 more level on top. One of our neighbors on the higher floors like to smoke at the living room window and many times the ash will fall and follows the wind into our house though our window. Which is the reason why our living room and bedrooms windows are 95% closed. Just last week we found another risk..

We received a surprise gift from our neighbor at around 11pm in our kitchen.
We've kept our kitchen windows 80% closed now, hoping we will not receive a bigger gift..

Now, anyone know who can I contact to return a gift?