It isn't all that hard to do fog lights on most GM vehicles. They use either an 880, 893, or 894 bulb. They are relatively small bulbs (so they aren't beefy) and are susceptible to moisture and vibration which can cause havoc with them and shorten their life. GM doesn't list them as A) they believe most people don't use the driving lights that much so the bulbs are *supposed* to last longer, and B) you'll come back to the dealership for service.
You may just have to crawl under the car with it jacked up or on ramps for the easiest access. In some cases (like the GTO), a 9005/HB3 bulb can be fitted in the socket in favor of the little 880/893/894 bulbs, but that is not always the case.
One thing for any of you to do to help them last, is coat the base of the bulb where it'll seat into the light housing with something like a moisture repelling grease. Heck, believe it or not... Vaseline! I was having problems with the GTP as the housing had started to melt from overheating, so there was a gap for water to work it'* way in, exploding the bulbs. During a rainy spat, I'd go through 2 sometimes 3 sets of driving light bulbs a week. I got fed up with having to stock up on 893'*, so I pulled the jar of vaseline out, lightly applied it to the based of the light bulbs, and put them in the socket. To this day, I have not had to replace them.
All the vaseline (or other suitable grease) does is fill in exposed gaps and repel the moisture.