Buyer kindly ordered a record from me yesterday. I took to Post Office, got home and saw the item - realised I'd sent the wrong one (they looked very similar). Sale price was in the very low tens of pounds.

In a fluster I immediately messaged buyer explaining and apologising. Probably stupidly I said keep the incorrect record as token of apology (it's worth a lot less). Just let me know when it arrives (and confirm it's the one I think it is) and I'll send you the correct one at my own expense.

Thoughts:  I know I've probably done this the exact opposite of the correct way!  But it's further complicated by noticing that the buyer has been described in feedback as not communicating, and has never left feedback for others.  That's fine - not everyone prefers to interact, but it potentially makes it tricky to resolve this one.

Any advice?