I have also had problems trying to buy Lindens using my credit card. I live outside of the US (New Zealand). Friday night I was able to buy using the Second LIfe Cashier, but have been refused twice since except today when much to my surprise yes sucess for about 3 mins. Lindens were charged to my credit card, and then credited in US dollars in my SL account.
I wanted Lindens not US dollars, and why could they not credit back to my credit card? I also have tier to pay in the next few days. I think Lindens are losing money not to mention in world merchants over what seems a total stuff up. I read this on the help page.
Intially the new payment system will be available to NEW residents ouside the US, and to those who do not have existing payment information on file. Soon the system will be available to existing Residents outside the US who already have payment information on file.
This does not make much sense to me. What are we existing residents with payment info on file supposed to do in the interim