FBA Return - is FBA worth it?

Peoples thoughts on this please.

Customer has raised a return over 30 days from receiving order stating a fault which is not a fault it is simply a function of the item.

Amazon accepted the return but have now marked the item as customer damaged.

They are stating as it is customer damaged they will not reimburse us.

So people’s thoughts on a) is this the actual policy and b) is that policy an unfair term?