Some time in late 2011, didn't Linden Labs make a big internal change to their payments system, claimed to make it easier for us foreigners. There's still some stuff on the forums from about that time about the end of that beta, but I have not been able to find any other info. There was some talk of using a third-party card-payment service to accept payments in foreign currencies, but my recollection is vague.
It is possible that some problems are connected to that set-up. What's the reputation of the third party, I ask myself. I have uneasy recollection of a few claims made at the time. Or was it the previous change, and no longer a current issue?
Paypal works for me. My card issuer refuses payment to Linden Labs. If Linden Labs gets awkward about my next Premium payment not being from a card, I am going to be wondering why I need to pay Linden Labs anything. I can hang out with friends for free. I'm not sure I see any advantage on the Support side for a Premium account.