My payment was declined due to the error below:
 Decline. Your credit card has not been charged.
The code error  Decline means a hard bank decline. A hard decline occurs when a cardholder’s bank refuses to authorize the transfer of funds. To fix it, contact the bank that issued your card and ask them to authorize payment to Zendesk.
For more information about code errors, see the article: Resolving issues when your credit card fails.