Royal Mail fee to pay

[lxwisgb]

I have received a card today from the Royal Mail stating that the sender has not paid the full postage amount, I have contacted the Royal Mail and have determined what package it is, it has come from Japan. Usually I would just pay, but money is a little tight at the moment. The fee requested by Royal Mail is £19.47.

I have contacted the seller to ask for them to reimburse me the amount before collecting the item.

Am I covered in any way if the seller does not want to reimburse me the amount?

(I may just be an idiot but I can't figure out any way to reply to norseway53; This isn't an import charge. I purchase items internationally quite often, albeit usually through the GSP, the card states "The sender did not pay the full postage" and the item is nowhere near expensive enough to cost £20 import.)