Card and billing details are changed in the payment provider's portal (Stripe or Paddle), opened from Billing; Avos does not store the card number.
Where to change
Under Billing, use "Manage payment". This opens the payment provider's secure portal, where you change the card, update the invoice address and tax details and see the charge history. The change applies to the next charge.
Who processes payments
Payments are processed by Stripe or Paddle, depending on the company's region. The card number stays with the provider only: Avos receives the payment confirmation and the last digits for display, nothing more.
Declined charge
If a charge fails, the provider retries over the following days and Avos shows a notice in the company area. Update the card through the portal and the next attempt goes through; access continues in the meantime.