The exterior of my cedar sided house in Alaska was professionally painted in August 2011. Sherwin Williams Duration paint was used on the siding. After one month there was extensive blistering, peeling, cracking, and streaking. It just gets worse as time goes on. Duration is their most expensive paint and is guaranteed for the life of the home. However, Sherwin Williams refuses to stand by their product. I have my doubts about whether the painter will come back and, even if he does, has the willingness and capability of fully correcting the paint failure. Since I will probably have to address the problem myself, I have three questions. First, was Duration a poor choice for cedar siding? Second, should I sand, scrape, or strip all the problem areas? Third, what paint product should I use after the wood has been prepped?
There's an old saying; "There's no such thing as bad paint, only bad painters." To that point, I'm guessing application errors are behind your problems. Preparation is key to painting siding, and your painter should've sanded, scraped, stripped and primed the siding before applying the first coat of paint. If the siding was damp or wet when it was painted, this could also be causing or contribing to the problem.
I'd contact the manufacturer directorly rather than working through the painter or the supply store. In my experience, Sherwin-Williams is usually extremely responsive. However, unless you deal with them directly, you might not get a straight answer.