It sounds like you're facing a challenging situation with your old Microsoft account and subscription. Since you are unable to access the account and have exhausted the recovery options, here are a few suggestions:
- Contact Microsoft Support: Although you mentioned difficulties connecting with support, it's essential to try again. You can find the appropriate contact methods for Microsoft 365 support here.
- Use the Microsoft 365 Admin Center: If you have access to the Microsoft 365 admin center, you may be able to manage your subscriptions and billing from there. If you can access the account on your old phone, try to navigate to the billing section.
- Proof of Ownership: Since you have proof of ownership, be prepared to provide this information when you do manage to connect with support. This may help in verifying your identity and resolving the issue.
- Escalation: If you manage to get in touch with a support agent, ask them to escalate the issue to the Account & Billing team for manual cancellation of the subscription.
- Check for Updates: Occasionally, Microsoft updates their support channels and methods. Keep an eye on their official support page for any changes that might help you connect with them more effectively.
Unfortunately, without access to the account, your options are limited, but persistence in reaching out to Microsoft support is key.
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