"Hello, is this Marc? This is Trevor from Quail; email was taking too long, let's just figure this thing out together." is my go-to phrase, and I've lost count of how many customers I've converted from almost-churned into the best possible evangelists through the simple mantra of "just pick up the phone!"
Absolutely solid advice.
It was kind of an unique situation because I was also a developer of the system that I was giving support for thus I really had inside knowledge and when things "looked different" I could tell them way they looked different and how it could benefit them in the new way they looked. I don't remember a single case in which after explaining the way people actually preferred the "old look".
I see that time as a highlight in my professional experience (should emphasize on my resume now that I think about it!)