See if the steps in this Turbo Tax FAQ will help. If not, contact an agent to process your payment.
https://ttlc.intuit.com/community/bugs-and-error-messages/help/error-we-are-having-trouble-validating-your-credit-card-please-try-again/00/26521
This FAQ will provide you the steps to contact an agent. https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number