eBay - should seller refund my postage?

I purchased a watch from an eBay seller and the listing stated the watch had 'been tested' and was 'working 100%'.

I received the watch and the day/date function was stuck so I paid to return the watch to the seller in England.

The seller refunded the total eBay invoice i.e. the watch price + P&P fee

Is the seller also liable for refunding to me the insured postage cost which I incured when returning it to the seller?

The seller said it's not possible to send more than the original amount, though they will offer me free postage on any other item they are currently selling. Though I don't want to buy anything else from them.

Thank you

Why don't you refer it to the eBay dispute centre. They make the rules in case you were not aware.

You could calculate the amount of postage and get them to send you the money through paypal.

you are responsible ,not the seller

I would have thought that as the item was faulty, ie not as described, the seller should refund whole amount including postage.