Please understand a couple of things. We DO install customers parts, with trepidation. We say that, for the reason that happened to you.
You came in ASKING for the diagnostic, our price is posted, and you sign for the ok to do it. Once we determine the problem, you are then given the opportunity to proceed with the work.
You mentioned that you had the part in your car. The problem comes from the inferior brand that you wanted us to put on. WE have had many dealings in the past with that brand and find out that they fail 6 out of 10 times in the first 6 months.
We will not install that brand on vehicles. It is not the identical pump as you mentioned, ours comes with a Lifetime Warranty!
We are looking out for our valued customer. If we had installed that part, without a warranty, chances are you would be in 6 months later upset with us.
We appreciate your patronage in the past, and We hope you understand our viewpoint a little better now.