I can see several issues with the seller.

1) They have a neutral for asking for more freight from another buyer, so the seller definitely knows what they are doing - it's not a one off error.

2) If you look down the feedback list, they actually did create a specific listing so that someone COULD pay the extra freight cost of about US$26! If you click on that listing, it shows as "freight" in the description.

My feeling is that these are not genuine feedbacks, other than the neutral. Maybe from friends and family because nobody is going to give a positive for having to dish out extra for postage.

I would simply get them to cancel the item by saying you do not agree to the extra cost, and then leave a big fat negative. Keep it short and sweet and don't put anything in there that would get it removed.