Customer return - Baby Products

Hello

I have sold a breast pump back in September for a total amount fo £100.

The customer has requested a return, which amazon has approved and refunded the customer the full £100 back in September. Its' now been over 45 days and I have not received the item back. I have tried to contact seller support and their response is:

Please be informed that the item is not eligible for reimbursement as it is policy declined unit. As per Amazon polices we cannot proceed further with reimbursement. See the FBA reimbursement policy page for more details.

The unit non returnable as it is a baby product.

Note: Reopening the case many times does not change the outcome as it is investigated thoroughly.

Does that mean the customer gets to keep the item and I lose £100? Seems a bit unfair!