I also attempted to get a refund on my account balance, but was unsuccessful. I followed the prompts and clicked "Refund entire balance" at the link (https://www.google.com/voice/billing/credits), and received an error message of "Balance Refund Failed. Balance refunds are currently unavailable for your account. Please contact Google Voice support for further assistance". The contact options led me to this forum and other automated help guides that did not resolve my issue. These credits were purchased within the past year. Please process my refund ASAP. Thank you.