Hey James,
You can get in contact with Billing to ask your question via the Cloud Platform Help center. Navigate by clicking on "Contact Us", then "Billing, invoices or charges", then "Support Package: Bronze". From there you can create a support ticket to get in contact with billing. From the top of my mind, I can say that I seem to remember that it's not possible to transfer credits. However, I'm not authoritative on this question.
Best of luck,
Nick