Buyer claiming not as described...not much I can do, is there?

[vixendaele]

I recently sold a package of "weight loss shake mix". It sold so quickly that it was still on my desk and I shipped it within an hour of receiving payment. But, that's neither here nor there. I just received a scathing message from the buyer stating that they were outraged because the shake mix was opened. It was not. I checked the seal before listing and again before shipping. 

However, I used the barcode scanner on my iphone when listing and was given the option of using a stock photo. Being an idiot (hindsight is 20-20), I did so. 

There's really nothing I can do but refund, is there? I certainly don't want the opened package back - I can't drink the stuff. The only thing I was thinking of doing was accepting the return in the original box and weighing it upon receiving it ... if it matches up with my original shipping weight, then I refund in full. 

Any thoughts/ideas/smacks upside the head welcome. 

P.S. This is my buying ID. 

[mr.elmwood]

Things I do not want back I simply refund and say "Keep it".

I have not had a screamer in quite a while. Thye do that because they think it is the only way to get what they want. I reply politely and calmy and they settle right down.