I will be in La Paz arround the 20 of August and stay between Bolivia and Peru until mid september. I plan to climb Illimani and other summits, looking for partners with mountaineering experience. You can join me nicolas.merou at laposte.net
I am French, 30 and fond of climbing and hiking, in south America for 6 months now and I have climbed a few 5000 and 6000m yet.
I jut got back from Bolivia. I climbed Huayna Potosi and Illimani. At first I was with climbing partners, but for Illimani I was solo. It didn't matter very much because the hide pairs you up with another climber, so you will definitively have a partner. I used bolivianmountainguides.com and they are fantastic. Unless you plan on climbing without guide, of course.
Good luck, Bolivia is an amazing place and there is so much more than just mountains. Check out my vids.