Whoever decided against you built a file to do it. Get it before you argue with it.
This is the single most useful idea in this whole method, and almost nobody does it.
When a company tells you no, that decision did not come from nowhere. Someone looked at something. A technician ran a diagnostic. A reviewer applied a guideline. A supervisor read a note. There is a file.
Most people spend their energy arguing against the answer. The stronger move is to ask for the file that produced the answer — and read it first.
Their record is often better than yours. It has dates you did not write down, names you did not catch, and prior complaints you did not know about.
They cannot easily dispute their own documents. Your notes can be argued with. Their notes cannot.
It shows you what they actually decided. Denials are written vaguely on purpose. The internal file usually says the real reason, in plainer words.
It frequently contradicts the letter. This happens more than you would think — the code on the statement does not match the reason in the letter, or the technician's note says something the service advisor told you it did not.
A denied insurance claim. Ask for the complete claim file, including the internal rules, guidelines, protocols and criteria used to decide, plus any medical opinion relied on. Depending on your plan type you may have a specific right to this at no charge — check what applies to you.
A car that keeps breaking. Ask for all repair orders, technician notes, and diagnostic session records for your vehicle, by VIN — including visits where nothing was found. "No fault found" visits are often the most useful thing in the file, because they prove you kept reporting it.
A contractor. Ask for the signed contract and every change order, the payment schedule, all invoices, and any permit or inspection records. Then check the public permit record separately — it is public, it is free, and it frequently does not match what you were told.
In writing. Short. No argument in it.
I'm requesting a complete copy of the file relating to [claim / VIN / job address], including all notes, records, and any internal criteria or guidelines used to make the decision. Please confirm receipt and let me know the expected timeframe.
Do not explain why. Do not argue your case. A request is not an argument — adding your theory only invites a debate instead of a document.
This is the discipline. Get the file, read it fully, and then build your response around what is actually in it. Quote their own words back to them.
An argument built on their record is much harder to dismiss than an argument built on your memory of a phone call.
That is information too, and worth writing down with the date. Note that you asked, how, and what happened. A documented refusal to produce records is sometimes more useful than the records would have been.