[BUG] Payment fails on both Free→Pro and Free→Max upgrade attempts and Fin AI Agent confirms it cannot resolve

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Title: [BUG] [Billing] Payment fails on both Free→Pro and Free→Max upgrade attempts — Fin AI Agent confirms it cannot resolve

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet (related: #57122, #55266, #55982, #56281, #45890, #50710)
• [x] This is a single bug report
• [x] I am using the latest version

What's Wrong?
Every attempt to upgrade my claude.ai account from Free to a paid plan fails with a "Payment failed" error. This happens both when attempting Free → Pro and Free → Max 20x — so it is not isolated to a specific plan tier or to the upgrade-between-paid-plans flow that other issues describe.

Steps to reproduce:

1. Log into claude.ai on a Free account
2. Go to Settings → Billing
3. Attempt to subscribe to Pro — payment fails
4. Attempt to subscribe to Max 20x — payment also fails

Troubleshooting already completed, all without resolution:

• Confirmed billing address matches card issuer's records exactly
• Confirmed 3D Secure/verification completes successfully
• Confirmed no VPN or IP masking in use
• Tried multiple browsers, including incognito
• Tried multiple cards
• Retried across multiple days

Escalation attempted:
Contacted support via the in-app Fin AI Agent multiple times. Fin confirmed it is unable to investigate account-specific payment issues or open a support ticket, and could not escalate to a human agent.

Expected behavior:
Payment should process and the account should upgrade to the selected plan.

Actual behavior:
"Payment failed" error on every attempt, across both plan tiers.

Additional context:
This is not a Claude Code CLI issue, filing here since it appears to be the most actively monitored Anthropic repository for billing bugs, consistent with #56281 and others.

Account email: dmengarelli.ti@outlook.com
Plan(s) attempted: Pro, Max 20x

What Should Happen?

Payment should process successfully and the account should be upgraded to the selected plan (Pro or Max 20x).

Error Messages/Logs

Steps to Reproduce

1. Log into claude.ai on a Free account
2. Go to Settings → Billing
3. Attempt to subscribe to Pro — payment fails with "Payment failed" error
4. Attempt to subscribe to Max 20x — payment also fails with the same error

Claude Model

Not sure / Multiple models

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

1.0.123 N/A — not a Claude Code issue, filing here per the repo's visibility for billing bugs

Platform

Other

Operating System

Other

Terminal/Shell

Other

Additional Information

_No response_