I run into the same issues. It's gotten so bad that I take meticulous notes when I talk to customers. For my product, I'm 7-8 week turnaround. And I tell customers it's an estimate, based on suppliers following through on their end. They don't get "estimate", they want to lock in a day, 2 months in advance.
I've had some tough conversations with customers. I'm a nice guy, but when I have notes and know exactly what I told you, you essentially call me a liar, it will not go well for you. Another thing I run into is customers will call one of my office guys trying to get a different answer. They're ruthless. The influx of yankees hasn't helped either. They're used to talking to people however they want. You're in the south now, it doesn't work that way here. I catch on to accents/attitudes quickly, and I have normal prices and also pain in the ass prices. If you're going to be a PITA, I'm going to make a chunk on you.
One of these days when I hang it up I'll miss what I do because I love what I do, but I won't miss the BS.