Too be honest I don't think she did too badly. It's very badly listed, with no description. A MINI buyer would be looking for phrases like Chili Pack, TLC and other recognised option names. As it stands the only options she seems to suggest it's got are leather seats. . So poor listing.
The whatcar site gives a trade in price of £9300 for a bog standard Cooper Conv. So assuming she has Chilli and the leather seats she may get 10,300-11,000 from the dealers trade in. The other options such as MFSW, chrono pack, and chrome line interior don't add trade in value in the dealers eyes.
So although she didn't get top dollar, she probably didn't lose out. If she was selling it back to her dealer, (as opposed to px), she wouldn't have got anymore.
Trade in values are down at the moment, as are Cherished prices. i can show you a Jan 08 Clubman S (DS/B, Web Spokes, Sat Nav, Full Leather, HiFi, bascially the launch spec car) with 3000 miles for £17800. That car was £24,500 new. It's on the cherished site.