I run support for a small SaaS and the hardest emails are the angry ones — a customer double-charged, or whose export failed an hour before a board deadline. My replies either sound cold and templated or I over-apologize and promise refunds I can't authorize.
Design a prompt that takes the {{customer_email}} and a short {{facts}} block (what actually happened + what we can offer) and writes a reply that: acknowledges the specific frustration in one human sentence, states clearly what we will and won't do, gives a concrete next step with a timeframe, and never admits legal fault or invents compensation we didn't approve. Tone: warm, direct, accountable.
A strong solution handles the case where {{facts}} says 'no refund possible' gracefully, and asks one clarifying question instead of making a promise when information is missing. Show it working on a genuinely hostile, all-caps email — no groveling, no corporate fog.