Can’t file a case review

That because account tampering cannot be applied since it on the Xbox servers not your console

It's not something you can unprove since your account is online

Not all suspensions/bans are eligible for a review and that is most likely the case for yours.

Because you already appealed and got.denied

Not sure why you want to file a cases review since you know exactly why you were suspended

And joo.just because your friend did it doesn't excuse the enforcement action

You are responsible for all actions on your account

If you have it on games haring maybe you should stop lending your account out

No one should have access to your private information and games haring is meant for families not people you don't know

If you're able to, you can try going to http://enforcement.xbox.com to see about submitting a case review for the suspension.

As far as the Ambassador program, you can email xboxambs @ microsoft.com (remove the spaces) to contact Ambassador staff. However, without a successful case review from the enforcement team, you most likely will not be able to rejoin.