[mothered]

They've said that from what they understand, Ive told them that the pen was missing from the case and that I need to send them a photo of what I received, and also return it.

So why not comply with their request?

You've claimed the pen wasn't received, so obviously you keep It.

Just wanted to make sure I don't mess it up .

And rightly so. When unsure, always ask questions.

Rest assured, you won't mess It up. It's standard procedure for many companies to request the return of the empty box/goods received, less the missing Item.