Pro and Pro Unlimited subscriptions: If your account downgrades to free before you are able to complete your purchase, please don't worry! We will not delete anything from your account. The oldest uploads (including their comments and stats) exceeding the limits of the free account will be hidden.They will be restored once you successfully upgrade back to your previous Pro account status.
You will be able to view your hidden tracks on your Tracks page like this:
If you would like to cancel this pending payment and try again when you are certain that your card will work correctly, you can cancel your plan through your Subscriptions page.