Amazon Fee 'Other'

As a seller (not a vendor) every 2 weekly payment cycle, i am charged 'Amazon Fees'. This is separate to the the 'FBA fees', 'Cost of Advertising' and 'Refunded Sales'.

This amount is greater than the combined fees (above) together and when I click on the breakdown, £25 of this is subscription fee and the rest is 'other'.

I have 5 open seller help cases without any reply - does anybody have any idea what this fee is?

I've checked storage and it's a minimal fee, 3rd party carrier fees are also minimal and it can't be gift wrapping