Additional Microsoft Defender tools and services that provide security across various platforms and environments
Did you read thorough the AI Answer and see the section regarding using the Sign-in Helper instead of the Recovery form?
"Since the recovery form has already been repeatedly attempted, do not simply resubmit the same information. Run Microsoft’s Sign-in Helper and enter the original account email address or phone number. It checks the account state and may present the applicable self-service action or an agent option."
Microsoft account sign-in helper | Microsoft Support
Note that it's possible the tool may offer an agent option that provides direct access to that channel rather than attempting to call directly, which is designed to fail, since if it were that easy to reach Support then the attackers would have the same easy method resulting in Microsoft Support becoming inundated with requests they can't typically use to verify identity, since that's not something that Microsoft accounts have never inherently contained.
The problem is actually obvious, but most people can't understand the true issues, since they don't understand that the typical 'proof' they hold is actually nothing more than account history, billing, or other similar information that the account itself contains, which the account thief now controls and of course has access to as well.
The deeper problem is that these thieves are professionals with complete technical knowledge of the Microsoft Personal account architecture, so unlike you they don't need to ask any of these questions and thus can act far more quickly to reverse anything you might try to do manually before you can use it to fully regain control.
Since you've indicated you don't really need the account, I'd concentrate on making direct contact via the Sign-in Helper tool, if possible, then be prepared to request that the Support you reach simply disable the account permanently, which is an appropriate request.
Often the Support reps can see that the account has been breached, but in order to protect them from being coerced or tricked by very well-prepared thieves or from often angry original account owners in various stages of grief over the loss of their accounts, Microsoft removed the capability for the agents to do anything other than provide explanations and aid in using the AI tools including the Recovery form that has taken their place.
The confusing part for consumers is they don't understand the simple truths I've laid out above and even though the Sign-in Helper tool page above tries to explain how to proceed, customers still seem to believe that the agents can do something they're not allowed to, specifically to avoid the human mistakes that often resulted in an account being lost.
The only thing that Support can actually do is to either block or disable the account, since that's the only manual recourse that's been left when they truly manage to determine that an account has been breached and is likely unrecoverable or in cases like yours where the recovery is less important than shutting down the ability for the thieves to abuse it further.
Rob