It happened to me twice and was fixed (once with pics for one item that I wasn't even selling! They stole a pic from either here or myspace. The second with my description that I sat there writing for about 20 minutes, I was so descriptive). Both times I just reported it directly to *bay...I didn't want the sellers to mail me some email with attitude, KWIM? And who knows if they'd even take it down anyway. But then the third time, this seller had copied nearly everything about my auction, from the layout to the wording about contacting me if under 10 fb, smoke pet and child free home, etc. I reported it once and *bay said they couldn't do anything about it because my auction was posted after hers. UM NO. So I contacted them again with at least TEN different auctions that ended in the beginning of the year, showing how she copied my wording and *bay said there wasn't enough proof that she copied me. OMG that made me mad. I never contacted her b/c it would be awkward since she's a TPFer and had purchased something from me in the past but still. It's the creepiest thing when someone is copying so much from you (including purchases). BUT, enough on that tangent.
Anyway in your case, since you know the seller, I'd contact her first and just say, "Hi, I noticed you copied my description without my permission. I'd appreciate if you would do so in the future" yadda yadda. Of course, the wording will depend on if you're ok with her using it after she has your permission or if you want her to write a new one.