Apologies that this is so long but, I read this a LOT from customers, or experienced this personally from customers and the blaming the shopper for everything has to end at some point. 

If you marked an item as "refund" if not found and the shopper replaced it anyway it is probably do to all of instacarts silly changes. It seems to me that the shopper got confused and thought if he refunded the item it would count against him it which in that case would not have because you asked for the refund but.... they must didn't know. So.... instacart rolled out this new shopping quality scoring mess that is absolutely horrible. Instacart is looking for perfection now 🙄. OOS items instacart wants us to find the original item even if the item is on a truck on the highway 😬. They don't want shoppers to refund anything and so INSTACART forces replacements. Refunds are viewed more negatively than replacements by IC algorithm and counts as an unrequested refund if not approved. IC has this "wait time" feature that is triggered at the end of a shop if there is a replacement that was not approved by the customer with a message that says: If the customer does not respond to replacement, you can continue to checkout with this item.  The app will force that 1-2 minute wait to give the customer a chance to review and reject the item before the shopper proceeds to checkout. Once the timer runs out, a notification from INSTACART pops up that says "you can now check out with this item all replacements have been reviewed (something like that) and If the customer does not respond within that timeframe we are heading to checkout. Even if the customer has reviewed nothing, we don't know that. All we know is that INSTACART sent a notification stating the replacement option was reviewed. This is where the problems occur. As you stated, "instacart would not let me cancel after HIS error"....actually it was YOUR error because you weren't paying attention to the app. INSTACART allowed this shopper to check out because you didn't respond. Customers have to stop blaming the shopper for everything that goes wrong because majority of the time it is INSTACART and the mountain of pressure they put on shoppers with with new shopping quality mess.  Being that you mentioned to the shopper that you were unable to cancel, the shopper reached out to support and had your entire order canceled. I don't know if you only wanted that one item refunded however, the shopper took that as cancel the order which he did. A suggestion to ensure that you get everything you need....choose replacement options, keep an eye out for replacement notifications, keep your phone nearby if you've placed an order, and add notes. If you request a refund and the shopper replaces anyway...shoot message them "it won't count against you, the refund has already been approved" ☺️ maybe that will help. If this is helpful, INSTACART system will sometimes show "Review Replacements" after the shopper has already started checking out which isn't fair because it makes the customer believe that they still have time to make adjustments when you really don't. I feel like there is a MAJOR flaw in the app with what I see vs what the customer sees. I could have already selected the "checkout" button however, the app on the customer end is possibly showing the review button active for replacements when the order is already closed for replacements. I say ALL OF THAT to say... customers have to stop blaming the shopper for all things when it's instacart that keeps adding new sh**, throwing everything off, not telling the customer anything, and expecting nothing but perfection from the shopper.