[BUG] Cancelling Max 20x downgraded account to Free instead of restoring annual Pro plan and incorrect refund amount issued

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?

Hi, I have a yearly Pro Plan with "Receipt # 2087-6914-2149":
Dec 3, 2025 – Dec 3, 2026 Claude Pro: €180.00
Total (including VAT): €217.80
Amount paid: €217.80

On 2026-07-01 (July 1), I upgrade to Max 5x with "Receipt # 2596-3832-8481":
Max plan - 5x: €90.00
Unused time on Claude Pro after 02 Jul 2026: -€76.17
Total excluding tax: €13.83
Total (including VAT): €16.73
Amount paid: €16.73

On 2026-07-02 (July 2), I upgrade to Max x20 with Receipt # 2476-4085-7905:
Max plan - 20x: €180.00
Unused time on Max plan - 5x after 02 Jul 2026: -€89.64
Total excluding tax: €90.36
Total (including VAT): €109.34
Amount paid: €109.34

On 2026-07-08 (July 8), I cancel Max - 20x with "Credit note # CPRQJQK3-0003-CN-01":
1 × Max plan - 20x (at €180.00 / month): €90.36
Refund issued (including VAT): €109.34
Total credit: €109.34

and downgraded to Free plan instead of Pro.

What Should Happen?

Instead of issuing the refund of €109.34 and downgrading to Free, the account should:
Receive a refund calculated by:

• adding €16.73 of "Receipt # 2596-3832-8481"
• adding €109.34 of "Receipt # 2476-4085-7905"
• subtracting the usage of the "Max x5" during 2026-07-01 to 2026-07-02
• subtracting the usage of "Max x20" during 2026-07-02 to 2026-07-08

AND

• continue the Pro subscription until 2026-12-03.

Error Messages/Logs

Steps to Reproduce

1. Subscribe to yearly Pro Plan on 2025-12-03
2. Upgrade to Max 5x on 2026-07-01
3. Upgrade to Max 20x on 2026-07-02
4. Cancel Max x20 on 2026-07-08
5. Watch the subscription plan not being Pro again

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.203

Platform

Other

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

_No response_