Generally, your bank will debit your account almost immediately, but the 'e-cheque' will not clear for up to 10 days.
Prepaid credit cards are faster, but do not offer the 'chargeback' protection that a real credit card does. Nor can Paypal offer complete buyer protection when either a bank account or a prepaid card is used . This also applies to money order and cash payments by the way.
This is a member to member Board, rarely visited by eBay personnel and not likely to be visited by your seller.
Contact your seller and explain the problem. Usually sellers expect immediate payment or payment within 96 hours (four days). Most will be willing to grant an extension to a new confused buyer.
If the payments have come out of your bank account, it makes no sense to repay from a card. Most likely the payment is in that 'between banking systems' limbo.
In future, your best choice would be to add a real credit card to your PP account. This gives you seller the immediate payment she wants, and allows her to ship sooner. And it gives you a double layer of Buyer Protection (PP and cc) against poor descriptions, damage and fraud, which are rare, but which do happen.