Granted a number of these points have probably been made but I can't be bothered reading all the silly posts - Some totally relevent i'm sure but the rest not so.. Anyway let me sum the situation up...
1) Out Of Control has gone double platinum and become their biggest selling studio album (700,000 copies ish) THUS if so many people already have their album sales for following singles are going to be lower. Although they have never had a single chart at number 10 before if previous albums had been as successful then they probably would have lower charting hits, in fact their 20 consecutive top 10 hits feat probably wouldn't be.
2) The song did get considerable promotion through a couple of TV shows and it also recieved great Airplay and TV Video play which are both forms of promotion so the lower position cannot be blamed on people not being aware of its release.
3) A single that peaks at number 10 is a HIT .. so why would anyone consider it a flop especially as it has recieved decent sales, perfectly satisfactory and inline with sales of previous hits... Can't speak french as example.
As far as the sugababes go.. I would say single number 2, from an album that has sold under 100,000 to chart at number 23 from an act as established as the Sugababes is a flop.. However, I don't think the sugababes are done and dusted yet