Hello people i am looking some advice please

A customer has ordered an mira advance J09A (electric shower) and put in a refund for “not compatible with system” when i have got the item back they have clearly taken new shower unit and sent there old shower unit back with my new cover on so it looks fresh. Serial numbers dont add up, after numerous messages to amaozn showing proof how serial numbers are different on box to shower unit i habe recieved. They accepted that customer has sent a different item, but conveniently the listing has been removed so because it is not active amazon cannot reimburse me? This was not my listing it was a generic listing many other sellers used to sell the same showers on. Can anybody offer advice how i can get reimbursed as although listing is not active i am still £270 down and left with a broken unit that is not mine.

ASIN is B078W8XNNL

This is the message from amazon about the listing

This ASIN has GTIN codes that do not match the brand associated to the ASIN. GTIN codes are reliable data that are used to limit duplicate products in the catalogue and ensure product authenticity. We verify the authenticity of GTINs by checking the GS1 database and GTINs that do not match information in GS1 are considered invalid. We recommend obtaining your GTINs directly from GS1 (and not from other third parties selling GTIN licences) to ensure the appropriate information is reflected in the GS1 database. If you believe we have removed your ASIN in error, contact Selling Partner Support here. Repeatedly creating ASINs for brands you do not have a relationship with will result in the removal of ASIN creation abilities.