Replacement parts Hasegawa

I bought Hasegawa Nakakima Jill yesterday from a local shop. The box had no cellophane, just this stickers to keep the top on, and the Sprues were not bagged. A few parts had popped off the Sprues in the box. No biggie usually, however one of the parts was small and is no where to be found. The part in question is one of the two engine exhausts.

I would like to order a new part from Hasegawa. I was wondering if anyone has done this and had a question about how to do it and how much I’m looking at for cost.

If it is too much of a hassle I’ll exchange it for the Nakajima “Grace” they had in stock

Edit: if anyone has a spare I’ll take it too!