Originally Posted by BWinmill
Another option is that Apple can refund the unused portion of the in app purchase and disable the remainder of the in app purchase. There's no good reason for them to deny the refund, within a certain period after the purchase, since they have everything locked down with DRM.
Apple have no way of knowing what 'potion' of the IAP has been used. The only role they play is in brokering the transaction. From their point of view it is a single atomic 'thing' that has been bought, they don't know if it was actually 500 gold coins, or one single item, only the app developer would know that.