To create a credit card update link for your client, please go to the subscriptions under the 'Billing' section, open the client's subscription for which you want to create a link, and click on the 'Get Update Card Link' button as shown in the below screenshot.
The generated link will look as shown below screenshot. You can copy and send it to your client.
The updated card through this link will automatically be set as the default card for your client.
Please email us at support@payfunnels.com if you have any questions.