If you want the site left in 'live' mode you can try entering these values to produce a DECLINED charge
370000000000002 American Express
6011000000000012 Discover
5424000000000015 MasterCard
4007000000027 Visa
These will produced ERRORS. If you put the site in DEMO mode, these will produce APPROVED transactions.
There is also a test credit card number that can be used to generate errors. THIS CARD IS INTENDED TO PRODUCE ERRORS, and should only be used if that is the intent. To cause the system to generate a specific error, set the account to Test Mode and submit a transaction with the card number 4222222222222. The system will return the response reason code equal to the amount of the submitted transaction. For example, to test response reason code number 27, a test transaction would be submitted with the credit card number, “4222222222222,” and the amount, “27.00.”
You can adjust LIVE vs DEMO mode by going to your storesetup.wws in your control panel.
