The blog post, issued on Friday, September 22nd, reads in full:
Due to some unexpected changes with our International Billing system, some Residents outside the United States with a Credit Card on file may have difficulty with their current payment method as of September 30, 2017.
In order to avoid any service disruption, we encourage all Residents outside of the United States to please take a moment to log into your account and re-enter your existing Credit Card information. Doing so now will prevent any disruption in in-world and Marketplace purchases, as well as recurring monthly billing for Premium Accounts, Private Regions and monthly Mainland maintenance. If you have difficulty with your payment method after September 30, 2017, updating your payment information will resolve the issue.
We apologise for this inconvenience and appreciate your patience as we continue to upgrade our billing systems in order to best service our Residents around the world. If you have any questions regarding this notice, please visit https://support.secondlife.com to contact our Support teams.
To re-enter your credit card details, go to your account dashboard at secondlife.com, click on Account (top left) and then on Billing Information on the list of options that opens. This will display your billing information summary (sample image below).
Make a note of the services the card is Used For on the right, then Remove your card details (option on the left) and then click Add A Credit Card (circled). This will open the form for you to enter your card details. Make sure to click Add Card to add the card to the system.
When your card has been recorded, you can check the details under Payment Method, then review the services the card is Used For. Should you need to change any of the latter, click on the Change option (circled under Used For on the right) to display a pop-up of services charged to the card and check / uncheck as required.