Email for a difficult situation

Act as a professional communication expert. Help me write an email for a delicate situation: [situation, for example chasing a late payment or replying to an angry client]. Context: - Recipient and relationship: [who they are and what our relationship is like] - What happened: [concrete facts, in order] - What I want to achieve: [ideal outcome after this email] - What I can't give up: [limits or conditions] Task: 1. Write the email: clear, neutral subject line, a first sentence that gets to the point, the facts without judgment, a sentence that acknowledges the other person's perspective, a concrete request or proposal (with options, if possible) and the next step with a date. 2. Write a firmer version and a warmer one. 3. Point out which phrases could trigger a negative reaction and how you avoided them. Rules: - Firm on the problem and respectful to the person. - If I share part of the responsibility, acknowledge it once, without over-apologizing. - No sarcasm, piled-up grievances or veiled threats. - Under 180 words per version; check it before delivering. - If an important detail about what happened is missing, ask me before writing. - If the situation would be better solved with a call or could have legal or employment consequences, tell me before proposing the email.