Why is my Pre Order Fixed Amount Final Value Fee always different?

[captaineverything]

I have sold two identical items(phone cases) two days apart and I have been charged a different Pre Order Fixed Amount Final Value Fee, 25p for one and 30p for the other?

After seeing this I have gone through my other sales and I have found another item(white shoe polish) that has only been charged 10p?

Why is it always different?

I am a business seller and I always thought that the Pre Order Fixed Amount FVF was 30p?

Any help appreciated

[plum993]

Maybe post here to get a better understanding  Business Seller Board - UK eBay Community

@captaineverything