timmmay:

 

It's clearly marked "quote" not "estimate".

 

You might be surprised to learn that may not be decisive in every case. I know this from experience as a lawyer and assisting people in preparing for hearings at the Disputes Tribunal at community law centres. Even if it's a quote, there can still be legitimate debates around what the quote was for and so on. Honestly, unless you have a lot of spare time, I wouldn't spend too much time arguing the toss over $500. Just choose someone else next time.