There are lots of reasons a payment could have been declined.
One of the most common is an AVS or address mismatch. It goes by the BILLING address, not your physical address. If you have moved recently and haven't updated your billing address, that will do it.
If you are paying with PayPal, the most common issues are not enough funds in the account, or that the person is using an 'ATM' card, and not a credit or debit card.
In both credit card and paypal transactions, mistyping numbers and wrong expiration dates are very common.
Lastly, with all of the fraud out there, you could be 'Declined' because your bank is looking out for you and has determined this transaction is outside your normal buying patterns
You can try to place a fresh order using a different credit card or payment method.
Declined orders will not be processed automatically, so you don't need to worry order with another payment option.
Lastly, if you are double charged, do not worry, we will get that taken care of for you.