I was permanently banned for no reason

If your account was truly hacked you would need to contact xbox support so they can do a compromised account investigation.

Support.xbox.com/contact-us

You should of got login notifications, and even account activity logs on your microsoft account that you're able to submit to them for evidence to prove you were hacked.

You would have to talk to the Enforcement team about getting a review on your account.

Their website jas more information and also it's the only way to contact them

enforcement.xbox.com

Bruh it called a “permanent” ban for a reason.

[quote user="Beans McMuffins"] I phoned customer support and he said there was
no reason why I was banned and I should post on the forums to get un suspended.

[/quote]

The support agent is incorrect. You were most likely issued a permanent suspension for the modified avatar since the only way to get that skin color is through unauthorized third party software via PC which is a severe violation
of the XBL Terms of Service.

You could contact support and have the do an Unauthorized Access Investigation but since our accounts are our responsibility at all times it may not affect your permanent ban at all. However it never hurts to try.