Ebay taking postage payment when i have to post myself

Hi,

 

I have sold an item which when packaged, ended up being bigger than the maximum package size for postage. I now have to take this to the post office and pay myself - yet ebay have taken the postage fee from my sale.

How can I stop this / get the postage amount given back to me?

If you paid for the original label (ie. had free postage on the listing) you can cancel it for a refund here:
https://www.ebay.co.uk/claims/simple-delivery/refund/seller

 

If the cost of postage was on the listing that means the buyer paid for it and that will be automatically refunded to them in 30 days.