Changing Membership Level Doesn't Cancel Old Membership Level Subscription with CCBill

[misfist]

Describe the bug
When a user changes their membership level, it correctly changes the membership and subscription on the site, but doesn't remove the previous subscription. This would cause a member to continue being billed for the previous level.

Essentially, a new subscription is successfully created in CCBill, but the old one isn't cancelled.

It's possible that this is related to the fact cancelled subscriptions aren't being cancelled in CCBill.

To Reproduce
Steps to reproduce the behavior:

1. Select new membership level
2. Complete checkout

Screenshots

Membership Changed in PMP

Subscription Changed in PMP

CCBill Subscription Not Cancelled

Expected behavior
The previous subscription should be cancelled in CCBill, so that only the new subscription remains active in CCBill.