Customer has bought an item and returned a different item

Hi all,

Sold a printer on here the other day £450.00 unit
We message the customer with a serial number of the product.

Customer ordered an item 5 days days ago and opened a return 4 days ago, stating its faulty and has a paper jam as per there IT guy so is faulty and must be returned.

So they have sent it back.

Today we have taken the printer out of the box (whilst it is the model of the printer we have sold)
the serial number has been removed from the back of the printer, the cartridges are the high capacity set and not that, that is sent with the printer.
Unknown to the customer, the serial number can be access on the printers control panel via the screen and the serial number is different.

Now I’m going to message them and just let them know they have obviously picked up the wrong printer and returned it, with images showing this.

Sad thing is this is from another business.

I would like to think this is a mistake, however removing the serial number is just down right fraud and the high capacity inks which are theirs.

What I want to know is no doubt they will open an a to z as soon as I send them this, what is the likelyhood of amazon refunding them?

and if they do who do i chase for the money amazon or the customer?

Thanks everyone.