Seller cancelled my purchase and says that I requested it to be cancelled. (Not true)

[ckarina46]

3 days ago, Igot a message from eBay stating:
"We're sorry to let you know that [**seller name**] canceled your order and mentioned the reason as 'Buyer asked to cancel the order'. The seller refunded $...... "

I had *not* asked to cancel the order, so I immediately sent a message to the seller, copying the message from eBay and adding: 
"But, I did not ask you to cancel the order. Is this a mistake? What has happened? Thank you!"

The seller has not responded, and there seems to be no way to tell eBay about this kind of situation. I mean, I didn't lose the money. But... this just doesn't seem right. I'm disappointed that I'm not getting my item, and I'm  frustrated that there is no way to tell eBay, "Hey, wait, this seller is lying."  I guess I can just leave negative feedback...