Sounds like you're in a bit of a pinch. We've picked up DNN for the same reasons, and usually after ~1-2hrs training, most of our clients can manage their own basic content updates. I have had the occaisonal client who just doesn't get it, and unfortunately there is no way around these. It sounds cynical, but the way I deal with them is to hit them where they feel it, and charge them for every bit of time it takes to make the updates. This usually acts as a not-so-gentle nudge to get them to realize the savings of them learning the system. I usually break it down as
- "Can you login to your Yahoo/Gmail/AOL/Hotmail account?
- Can you use MS Word?
- Then you have all the skills neccessary to change the content on your site."
However this only applies to websites with a majority of textual content. The next question for the designer is, even if you've deployed DNN, is the design (overall, not just graphic) user-friendly and implemented in a way to complement their content and not complicate it? Early on, I made the mistake of trying to solve alot of solutions by custom-writing modules in xMod, and while powerful it sometimes can make things a bit too.... obtuse... for the general user.
Basically, try to actively listen to what your customer is asking of you and nudge them in a logical direction. I do understand your frustration, I just had a customer (who I've requested for digital files FREQUENTLY) bring in updates for his website as printed-out MS Word documents that he'd cut up with scissors and taped into the layout he wanted, and hand-drew several diagrams which I'm having to go over and re-work in Illustrator, so I feel your pain.
SB