Open the back. look into it and see.
Its just how it work, its also up to you to make sure you get what you ordered..
You made a mistake by not doing that,
So if you can make mistakes so can others, including not including that what ever it was. not really sure you where scammed a lot can happen might have been a mistake the same way you made one.
Most likely it was. the little kid serving you get nothings from not adding it, but the chance kids in a stressing place make a mistake is sort of big.