Final notice + stop-work — invoice 30+ days overdue

An invoice is now 30+ days overdue. I've sent the polite first nudge and a firmer second. This is the final notice before I pause work and consider debt collection. Help me write it firmly without burning the relationship if there's any chance of saving it.

Client: {{client_name}}
Invoice + amount: {{invoice_ref}} — {{amount}}
Original due date + days overdue: {{due_date}} ({{days_overdue}} days)
Prior chases (dates + summary): {{prior_chases}}
Work currently in progress for them: {{wip}}
Stop-work date if not resolved: {{stop_date}}
Final pay-by date I'm setting: {{final_pay_by}}
Will I offer a payment plan? If yes, terms: {{plan_terms}}

Write a 180–220 word email.
- Subject: "{{invoice_ref}} — final notice ({{amount}})"
- Open: state plainly that this is the final reminder before formal action. Lead with the amount.
- One paragraph: prior chases, summarised. No emotion.
- Clear ask: pay in full by {{final_pay_by}}, OR reply with a written payment plan I can accept.
- Consequence paragraph: what stops on {{stop_date}} (work paused, files held, debt referral). State it as a fact, not a threat.
- Close with: "I'd much rather resolve this with a quick reply — even a payment plan is fine."
- Sign-off as {{your_name}}.

Calm, factual, AU English. No exclamation marks. No "as you can imagine".