I bought a hard drive from someone a while ago. Since it worked well I left positive feedback. I also sent him a message pointing out that he was selling several of them and not offering a combined postage rate, and that I would have probably bought two if he'd quoted one.

He promptly left me "positive" feedback that read "WARNING Buys then complains about posting .which was stated and never changed"

A: I never complained about the postage.
B: I never asked him to change it, I simply pointed out he'd sell more if he didn't charge £4 per item for multiple items.

I'd be more upset, but it told me to add him to the list of vendors I will never use again, and people I will never sell to, and in any case eBay don't stop you from deleting positive feedback; it ought to go in 24 hours, and I get to keep the rating, it's just the comment that disappears.