I'm sorry you're experiencing trouble purchasing credits, especially since your card ending in 8080 is already on file and auto-reload is enabled. The error message "Failed to purchase credits: Invalid payment details" suggests there may be an issue with the payment method itself, such as an expired card, incorrect card details, or a restriction from the card issuer.
Since I do not have access to more specific troubleshooting steps or account details, I cannot provide a direct solution to this issue. If you have recently updated your card or billing information, double-check that all details are current and correct. If the problem persists, you may want to try a different payment method if available.
Please let me know if there are any other details you can share or if you have additional questions!