[Billing Bug] Charged extra usage due to caching failure (1M token compaction) + 2 day outage - Support Refusing Refund

Preflight Checklist

• [ ] 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?

Bug Description
I am reporting a critical billing bug affecting Claude Pro accounts where the prompt caching system fails silently, causing "Extra Usage" credits to be drained at 10–20x the normal rate.

Evidence of Bug

• Financial Loss: I was charged £15.30 in extra usage fees over the last 48 hours.
• Token Compaction: My usage graph shows a spike where 2 messages consumed my entire allowance, followed immediately by a system "compaction" event that freed 1,008,000 tokens
• Service Disruption: For 2 days, I have been limited to 2–3 messages per session due to this bug, rendering my Pro subscription unusable.

Support Response
I contacted support regarding this confirmed technical error. The AI agent ("Fin") acknowledged the issue but refused a refund, citing "non-refundable terms" despite the charge being caused entirely by a platform-side caching failure. This contradicts Anthropic's recent actions in April/May 2026 (e.g., the HERMES.md bug) where full refunds + compensation were issued for identical billing routing errors.

<img width="310" height="284" alt="Image" src="https://github.com/user-attachments/assets/22ffa602-3388-4f1f-888e-c994f127ca53" />

<img width="744" height="298" alt="Image" src="https://github.com/user-attachments/assets/46976016-32b8-4c89-ba1a-8119839c3112" />

What Should Happen?

1. refund of the £15.30 erroneous charge.
2. Restoration of my Extra Usage credits to pre-bug levels.
3. Confirmation that this account has been flagged to prevent recurrence of the cache breakage.

Error Messages/Logs

Steps to Reproduce

Any usage with long context chats during this prompt caching issue will reproduce over usage.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.128

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_