Western Union® Auction Payments has made a business decision to no longer accept MasterCard® as a form of payment. You may still use your Visa® or American Express® debit or creditcard, but if you have MasterCard® stored in your account profile, you should sign in to Account Central and delete your MasterCard® information. We're changing our name back to BidPay®. Watch for our name change and updates to our website coming soon.
Of course I don't know the reason for this, but I'd bet it has something to do with the rampant fraud and chargebacks associated with 3rd party online credit card processors like BidPay and PayPal. Some credit card issuers are now refusing to permit chargebacks to these 3rd party processors because the fraud is so out of control.
This that know me know my disdain for PayPal and what a scam it is... but in case you've forgotten, visit PayPal Sucks for some horror stories.