At Appointy we don't save any credit card information. Entire payment activity is handled by PayPal. There are two ways one can update their subscription credentials for Appointy:
Case 1: (If you have paid through your PayPal account) Login to your Paypal account and update your credit card details.
More help can be found here https://www.paypal.com/helpcenter/main.jsp?locale=en_GB&_dyncharset=UTF-8&countrycode=GB&cmd=_help&t=solutionTab&solutionId=163157
Case 2: (If you have paid through credit card) You can let us know your Appointy username and we will cancel your Appointy subscription. You can subscribe again with a new credit card.
Please note: Canceling a subscription will not effect your account data.
Please reach us at firstname.lastname@example.org, in case you have any trouble subscribing to Appointy services. Our team will promptly address your concerns.