Be thankful they didn't pick up first THEN open an item not received case. You should only accept cash for pick ups because you can't supply a tracking number. I had a buyer open such a case after pick up, before they even got out of the carpark, within minutes of collecting. Fortunately for me, that was at a time when paypal assessed each case and/or buyers and sellers on their merits. Not anymore. It's all run by bots now so be careful.
Already been advised how to cancel the transaction, I'll just add that when you do, you'll be prompted to 'cancel and refund'. Even though you have already refunded, you have to select that. You won't double up on the refund, just another stupid thing they have inserted to confuse sellers.
They will then drag out the cancellation until it rolls over into your next billing cycle so you have to wait a month to get your fees refunded. That's been my experience anyway
