I don't see how Diana Vickers has underperformed or flopped.
Shes had a number one single and number one album, along with 2 other top 40 hits, and has sold Half a Million records with combined singles and album sales in just 8 months, and don't forget this is from an x factor finalist who finished 4th.
Also, shes had rave reviews in the west end and has also done several charity events.
If Diana does flop after album 2, she always has her acting career to fall back on, plus her modelling career, so I think we're stuck with her for a while.