Paypal has my credit card information. Why doen't paypal use my credit card to pay for shipping charges when funds aren't available in my account? This would allow my buyers' to receive their goods two or three days sooner.
Single shipping labels allow you to change funding source.
MOS always tries a bank transfer first and does not give any choice to use credit card. I have reported the issue to MasterCard and Visa as a merchant agreement violation several times (if you show the logos, you must accept the card) - but they must not see it as a priority or PayPal would have been required to change it by now.
