[seriousmass11]

Is there a way to fake a Amazon denying refund mail?

For what purpose? A credit card chargeback? I would NOT do this. Take the loss or return the item for a legitimate return. Mail fraud and bank/cc fraud's never needed.
If it's for some other reason, can't you just edit the page and screenshot or print as PDF?

it’s for a serial numbers SE I’m doing and the company is requesting either live chat message or mail proof of not getting replaced/refunded