Mac Studio M4 Max order not upgraded as expected

Apple standard policy for direct-from-Apple purchase satisfaction is ONLY this:

You have 14 days from receipt to return your Apple products for a full-value refund or exchange, in the same country as the original purchase.

This is your only recourse in the US and MANY other markets.

Sounds like you misinterpreted something, because in August the new M5 Mac Studios weren't even announced yet, so there would have been nothing at that time to upgrade to.

What did this email about "automatic product upgrade" say exactly?

If the email was sent in error, they might not have known about it so would not have sent an email correcting the issue.

Also, not entirely sure what you expect this user to user forum to do about the issue.

Then you can rest assured that the system you own is the best that was available when you placed your order.

Computers will always be generally faster, better, and cheaper if you wait.