As you probably know, G-Charts are no longer made or supported by Garmin so even if you do find one it will be out-of-date. I have occasionally seen them on eBay where they get fought over and end up going for ridiculous money ( but I have never seen a Greek one ). Is there a Greek version of eBay ? As far as I know nobody has ever successfully reprogrammed a G-Chart cartridge. You may be better off putting your money towards buying a newer GPS/Plotter.