Seller adding extra charge

[many*splendid*things]

Hi, I've just received an invoice from a seller for an auction that ended last night and they've added an extra $10 charge (see below) without any explanation.

There's nothing in the listing about any additional charges (ie. packing/handling) and post was clearly indicated. I'm assuming this is a surcharge ie. paying seller's ebay/paypal fees.

I understand this is against the rules and can be reported. Is that what I should do if the seller won't remove the charge from the invoice?

I haven't done so as yet but I was going to send a polite query to begin with.

I don't really want to be in a stand off situation where they won't remove the fee and I don't pay (and have a non-paying case opened - even if I could appeal to have the strike removed later). Am I better to pay first and then report the surcharge?

Or, if I report it to ebay first (assuming the seller won't remove it) would they make the seller remove the charge so I can pay the original amount?

If anyone can offer any advice on how to deal with this situation it would be appreciated, as I've never had a seller just throw an extra charge on top like this (I didn't even know it was possible).  Cheers

Item (1)	AU $133.50
Postage	AU $22.60
Seller extra charges	AU $10.00

Order total

AU $166.10