Nothing wrong with backing down and walking away.
In fact, it's really the only option that makes sense to a business owner.
No good can come from escalating the confrontation.
When I writing estimates for my brothers shop (body and mechanical) I would name the price, and if the people wanted to discuss where the number came from, no problem, I would show them all the line items, especially where I had reduced costs to their benefit.
If they wanted to argue, I would tell them sorry that I couldn't tell them what they wanted, but they were perfectly welcome to go to a different shop and inquire there. Then I would turn and walk back to my office.
The best part is when some of those people would come back after getting higher estimates elsewhere (I really did try to make all my sheets as fair as possible, so I was generally lower than most other shops in the area)
They would come in and tell me they were ready to get the repairs done, and if I felt they were DB enough, I would tell them we were too busy and so sorry... just can't fit you in.
We also towed for local and State PD... those people were a whole different bag of douche...
