Received items with stains - refund advice please (NO PERSONAL INFO)

First time I've had an issue with an item I've purchased from Vinted (along with one from Depop, so bad luck this week).

The item I've purchased arrived with a number of stains, which were not disclosed in the listing or pictures for the Very Good item. Raised with the seller and agreed a partial refund, as I really like the item and the partial refund will go towards dry cleaning costs.

The seller is now saying that they will cancel the original order and relist for the lower price. Is that the right way to go about it? Will I end up paying postage again for something already in my possession?!

Any / all advice much appreciated!