Yet another "1 post dude" signing up to say thanks.
This is the third (maybe 4th) Play and Charge kit i've had this issue with. Earlier this year i had a ridiculously long instant message conversation with Xbox "Support", who slagged Amazon off, and basically told me i had to keep buying new ones until i found one that wasn't broken.
Then after not using my console for a while, the problem comes back. I was gutted, until i found this thread.