This is more of a “gee I learned something”. I ordered 20 boxes from the wholesaler and only had shelves for 16. The order flagged as delivered and it appears I was charged, however the order was not delivered. When I looked, it was scheduled for the next morning which is when I did receive it (after purchasing additional shelfs). No issue with this, it just had me concened briefly while I figured it out.
In this case you will only get charged for the delivered items (plus the delivery fee of course). Those items which didn’t have space on your shelves are automatically refunded.