Why do you expect a credit to be issued for the canceled service? A service cancellation is a removal of the service. A service downgrade would be a change to the term, period, renew date, or service options that result in a prorated price change whose total is less than zero.
Depending on your changes, it's possible to receive a credit larger than the total amount of the initial invoice for the service's original term and period.
Consider a client orders a service:
- 1 month, $5.00 (30 days in length)
- You update the service to change the renew date to a day later (service is 31 days in length).
- You update the service to change the renew date again to the day after the creation date (service is 0 to 1 day in length, depending on time of day). Prorating this change would prorate 31 days for a service whose term and period equates to 30 days, resulting in a credit of [(31 days * $5.00) / 30 days] = $5.1667 ($5.17).
This may not be the best API request to make as it both cancels the service and changes the renew date. The renew date change is prorated, and the service is immediately canceled.
As I mentioned above, a service cancellation is not a downgrade, so there is nothing to prorate.
No service data has changed, so there is nothing to prorate.