If you paid via paypal then you certainly need to contact paypal as stated above. Ebay would not have access to the reason why the payment hasn't gone through as they wouldn't be able to see into the account, so they have merely suggested to you the common reasons for payment pending.

If you paid with a different credit card in your own paypal account I would guess this might be part of the reason?

Otherwise if you paid by credit card directly with the seller then you would need to contact them.