Now that I don't have balances on my prepaid Greek phone account, I needed a way to get a refill card before arriving at the Athens airport.
https://www.telesuite.gr/eshop/ sold me a 10€ topup card for 10.88€ including commission. I also needed to get approved by their security before I could buy. After nothing happened I used an on-line chat from their website to get approved.
It is cheaper to buy codes from a kiosk, but I lost the slip I bought in Sept. My phone is now topped up and ready.