We just got back from a week in Provence in June. We took our Santana triplet with us and did day rides from our base in Isle sur la Sorgue (great town, btw).
I haven't used the service that NoGaBiker mentioned, but while we were in Provence I stopped at their shop at the foot of Mt. Ventoux in Bedoin. Nice folks to deal with (I was looking for a replacement crank for the stripped out Octalink crank on my tandem) and they seemed to have a good variety of rental bikes, including a nice-looking Cannondale tandem. I'd be surprised if they couldn't point you to a luggage service if they don't offer one.
Have you tried Googling "provence self guided bike tour"? I just did, and it comes up with a lot of suggestions. Self-guided bike tours are very popular with Europeans (especially Germans) and usually offer luggage transfer, pre-booked rooms, and rental bikes. You are on your own with the riding part (no guides).
An Austrian company that does self-guided tours in France is Austria Radreisen: http://www.austria-radreisen.at/radtouren/index.htm
They are very well regarded for their tours, from what I understand.
I did see lots of tour groups while we were out and about. Most seemed to be German or Dutch, but I'm sure they could accommodate English speakers, too.