If you can't pay from your refund, then you can visit the nearest U.S. Embassy or consulate office to purchase a pre-paid VISA card on a U.S. bank. All U.S. Embassy's have a U.S. banking facility in them, and most U.S. consulate offices do. So if a consulate office is closer to you, call them to confirm they have a U.S. banking facility. Make sure you purchase the card is U.S. funds, and not in the currency of whatever country you are in. Otherwise, the card will not work for paying TurboTax.
After purchasing the prepaid VISA, register the card online with any ***VALID*** U.S. mailing address and a ***VALID*** U.S. phone number. You may need to wait a few hours after registering it, for the data to propagate to where ever it needs to propagate. Then you can use that card to pay your TurboTax fees with.