We are sorry you are having this issue.  This does not happen often but, unfortunately, this is most likely a PayPal or Credit Card Carrier issue.  There are three approaches that might help...

PayPal issue...

If you have ever had a PayPal account then their system will recognize the email attached to the transaction and want you to log in using your pre-existing account.  You can contact PayPal if you do not remember your account information.

Credit Card Carrier issue...

If you have never had a PayPal account then it is possible that this is a credit card carrier issue.  It can happen that the carrier will not let certain transactions go through depending on your account security. You will then need to contact your credit card customer service and let them know that this is a valid transaction. 

Trying another credit card...

You are welcome to use a different card to pay for your transaction.

Last but not least...

Your Auction chairperson has the capability of manually posting a payment (Cash/Check) to show that your item(s) has been paid for.