Seller shipped item using wrong label

Level 1

So I purchased an item and the seller accepted offer then after 5 days the transaction got cancelled, but right away seller let me know he's on his way to ship item to send a new offer. I sent an offer he accepted. I received the item yesterday everything is perfect BUT I noticed he sent item using the old shipping label from 1st transaction that got cancelled. Now OfferUp is sending him reminders not knowing he already shipped it using old label. What should I do I don't want him to not get his money when he didn't do anything wrong. I already contacted OfferUp but they haven't feacrea back. I also send messages to seller which he hasn't read and only has 1 more day B4 transaction gets cancelled

Level 3
I do not know, how much the item cost to ship, but,it seams that someone is going to take a loss. If, that is what will happen, perhaps you can split the loss between both of you? Just a suggestion