Giving Diablo carry for in game gold is not against TOS.

You would have to check the enforcement site to see about submitting a case review. That is the only way to contact the enforcement team. https://support.xbox.com/en-US/help/family-online-safety/enforcement/how-to-submit-a-case-review

If you were posting that in an LFG post, then it does violate the rules. LFG posts are only for looking for people to play a game with and should essentially only be "I'm looking for X amount of people to play this game". Offering to buy/sell/trade, etc. anything is not permitted in them.

Can you show us where it says that in the code of conduct please?

G. Protecting your account and personal information

•Protecting your account information is extremely important; do not give out your own personal information, including but not limited to: phone numbers, email addresses, physical addresses, etc.

•Use discretion when deciding to share your name and location in your profile and when recording or sharing content you create. If you wish to share any other personal information with another player, please do so by a non-public method.

•Do not lend, transfer, sell, or otherwise provide access to your account.

•Failure to properly secure your account could result in loss of access to the Xbox Live service.

•For additional information about making your account more secure, visit our account security page.

Yes, it breaks the code of conduct to ask for personal details on xbox live.

Every "custom" content you attempt to add in this direction is considered tampering as it goes against Xbox live service rules and you risk being banned for this reason