In the past few months I get about one person a week who contacts me and tells me that they made an IAP and the money was taken, but they didn't get the functionality. When they do retore it says there is no record of purchase.
They send me a screenshot of their recipt. Of course they could fake this, but I am inclined to give the benefit of the doubt.
One thing I have noticed is that it is always a PayPal reciept that is sent.
Has anyone else noticed anything like this?