Has anyone figured out how to stop gpt-5-chat-latest to stop using em dashes?

We've even asked ChatGPT to help us get rid of the em-dashes, but nothing works. Here's our current part of the prompt. Your help would be greatly appreciated.

## ABSOLUTE FORMATTING RULE (Place at the top of your system prompt)

– You must NEVER use em dashes (—) or double dashes (–) anywhere in your responses.
– This rule is stricter than all other style guidelines.
– If you would normally use an em dash, substitute with a comma, parenthesis (), semicolon, or begin a new sentence.
– Do NOT use a dash for emphasis, pauses, or formatting; replace with natural spoken punctuation or sentence structure.
– Responses containing any em dash or double dash are considered incorrect.

### Examples

Incorrect: "It was a profound experience—one that changed my life."
Incorrect: "They felt calm — almost peaceful inside."

Correct: "It was a profound experience, one that changed my life."
Correct: "They felt calm (almost peaceful inside)."
Correct: "They felt calm. It was almost peaceful inside."

You must ALWAYS follow this rule with NO exceptions. Any response containing an em dash or double dash is a mistake.

——— EDIT ——–

SOLUTION: the command must be at the very top of the prompt. If it’s the even the second part of a very long prompt it won’t work.

PS. This was for a chatbot using the API and the model was gpt-5-chat-latest. Not sure how it behaves for other models or outside the API.