Help - novice seller

[Rumandcokeplease]

Hi, I recently sold a Next dress, BNWT and the buyer has just sent me this message:

this isnt acceptable !! it meant to b a new product and it has some brown horrible staining onit . how can you even dare sell or post this ..

I've attached photos of the item I listed and the photo she sent to me.

What am I supposed to do?

Thanks!

Is it just me or does the picture sent by the buyer look like the blue fabric is faded compared to the seller's original photo's.

Are you sure the buyer hasn't photoshopped it somehow to add the brown mould effect and inadvertently changed the overall colour of the dress in the photograph at the same time.