You inspected the plane before you bought it! And you accepted the condition. The fact is that hobby shops run on a shoestring budget, especially if they are RC only. If they take the plane back and one single thing is missing, they can't get their money from the manufacturer. Some businesses that do a lot of volume will take that chance but a hobby shop simple can't afford to. That's why they let you inspect the contents of the box before you took the plane home, so that you could reject it before leaving the shop. As said above, get in touch with the manufacturer and get them to fix it. If you send some pictures to them, you may even get new parts sent without having to send the old ones in. That'll give you spares which is even better than what you have now.