This site is regularly scanned for vulnerabilities. All payments and private information are certified VeriSign Secured and all information exchanged is encrypted.
SAi does not store any credit card information. You can create multiple payment profiles. These do not actually store your credit card information, but rather a token that can then be used to call the credit card information that is stored with the financial institutes.
SAi accepts Visa, MasterCard, American Express and Paypal. In some countries (such as the USA) a debit card can be used as a credit card, as long as the debit card has an accepted credit card logo printed on it.
To update your payment information, click Manage Payment Profiles in the Manage Subscriptions Dashboard.