Battery explosion, magsafe issues.

Hello,

Firstly, I would like to say that the quality of the magsafe adapters is terrible.
I bought my second after my first went 'pop'. This cost me £60, and within a few months the cord has become loose, exposing bare wiring. I understand this is still within warranty, but is nevertheless unacceptable.

Secondly, and much more importantly, recently I have bought a new computer and have not been using my Macbook as much. However, today I attempted to charge it so that I could play a game that is not installed on my PC yet. It was plugged in and seemed fine. I did not notice anything strange while booting, however when trying to launch the game, the laptop abruptly turned itself off. Thinking this was odd, I unplugged it, only to notice that the battery had a noticeable bulge.
I immediately removed the battery. The casing has warped substantially so that the individual battery packs inside are visible. The front casing has also warped away from the main body.

I am at a loss to explain how this might have happened. I also cannot find any way to e-mail apple about this, as the support pages are all circuitous and suggest I call a premium-rate number.
Any suggestions as to what I can do now would be greatly appreciated.

I bought the laptop only around a year ago. I believe I have an applecare plan, although I probably did not register it and cannot remember exactly where it is.