Complain to a supplier and get it put right

Help me complain to a supplier.

Supplier and what I buy: [details]
What went wrong: [facts, dates, order numbers]
Impact on me: [lost sales, staff time, unhappy customers]
Has it happened before: [details]
What I want: [replacement, credit, refund, a change]

First ask me up to 3 short questions. Wait for my answers.

Then:
1. A firm, factual complaint email with a clear ask and a date.
2. A short phone version.
3. A follow-up if they don't reply in a week.
4. What to keep as evidence.
5. When it's time to look for another supplier.

Only use what I've told you, leave blanks for anything I haven't given, and don't invent facts or figures. UK English.

Stay in this ChatGPT chat. Do not turn on apps or connectors, and do not use memory from another chat.