Actions To Take
If you have sent your products to your courier, but they have not been shipped yet, you would need to ask your courier or shipping company to return the goods, or preferably, if they can, to help you relabel all the items that were mistakenly labeled, this would be the easiest and fastest solution, so Act fast.
The biggest problem, in this case, is that:
The shipment in question after being received at Amazon warehouses might have no problems to resolve.
If there are problems and you have an opportunity to reconcile the shipment, you will not be able to reconcile until after 30+ days!
By the time you want to resolve whatever mistake, your mislabeled products are out there to the public and ready to be sold!
If you do not do anything, the problem will escalate to a bigger one, you will notice more returns and customers complain, eventually, your listing will be stopped by Amazon, and your account health might plummet. so you do not want to get here at all.
The Shipment Process
When creating a new FBA Plan, you have 2 choices of how your products are going to be packed,
Case Packed means that all items in one case are similar, so you would label all items inside the case, and label the outside of the case with the FBA label that has the FBA shipment Id and indicates what SKU is inside and how many.
If you sent a case-packed item, Amazon most likely will ignore what label you had on the individual products inside the case and add the SKU found on the FBA label to its correspondent SKU in the FBA inventory.
Individual Items mean that one case can include one or more items mixed together. The FBA label that is on the case would include everything found in the case packed except the SKU, and that's because you could have many SKUs inside one case.
In this case, Amazon will follow the labels of each individual item and add them to the corresponding SKU found in the FBA inventory.
The Proper Actions
Watch carefully the inventory levels of the questioned items to make sure what shipped SKU added to what SKU in the inventory.
Once you are aware of what exactly happens here are your choices:
if the mislabeled product was added to an item that has no previous inventory
Change the whole title, description & pictures to correspond with the new item
if the mislabeled product was a quantity variation of the existing SKU
Change the product title/description to the lowest quantity. so If your regular SKU is a pack of 2, change it to a Pack of 1 and accept that there are items that are actually a pack of 2.
If the sent item was a pack of 3, then keep the title the same.
The point is that the customer will receive more than what he ordered.
if the mislabeled product was a totally different item than the existing one.
This is the worst case, unfortunately, the best solution in this case is:
Stop the listing
Make a removal or disposal order
Get Rid of the Inventory FAST
The main point of doing what we have done is to get rid of the inventory but with a minimum loss, so:
Create a coupon with a 50% to 70%+ discount
Keep increasing the discount every 48 hours if you see no good velocity in sales
Advertise the listing as a last resort
Calculate your net income, if the cost of sales is more than returning or disposing of the items, then you better do that.
Failure to do so will jeopardize your account health, will cause many returns and bigger losses, and eventually an unhappy customer experience.