90-100 degree celsius? Were you playing in your oven or something? That is way too hot. I would definitely just let Dell sort it out regardless of the price, because buying a new adapter isn't gonna cut it - if your GPU is running at 100° while playing WoW there is something wrong with your hardware or your fans, and not letting Dell do the hardware work is most likely going to cost you a new laptop.
And even if the GPU is not the culprit (which it probably isn't but hey) and you manage to fix the power problem, please have a look at your fans or something after, your laptop is running too hot.