Client support, we've heard about it
“I paused for effect,” Newt wrote, “and then replied. No. I don't think you're an idiot.” And then he walked away.
Having been on both sides of a discussion like this, I can only say that 99% of the fault here is Newt's and his manager's (and I will let them apportion the blame any way they see fit).
Any substantial change of the UI will confuse the end users, no matter how intelligent or knowledgeable they are. It is the job the IT department to make sure end users understand the changes, and to walk the users through the changes if they don't. And then do it again and again, when and if necessary. And it will be necessary - any work process you've been using for years ends up wired to your bones. People will automatically revert to it given a slightest chance, and then will be confused and angry when it does not work (I speak from experience here!).
Absolutely the worst thing an IT support person could do is to be condescending and snarky towards the end users: when all is said and done, the reason any organization or company exists is the work done by these end users. Without that work and these users there will be no company, and no IT support to go with it. If you are feeling snappy (and everybody has bad days) it is better to find something else to do for the day, and to pass the direct support tasks to one of your colleagues. If you feel snappy all the time, then it is the time to move on: the IT support is not for you anymore.