It's not the best, it's actually the only available prepaid plan in case you will be using a lot of data. If you need less volume, all carriers have plans from 30-100MB per month.
What they told you from the CC of Wind is valid, it's the same plan I use when I'm in Greece. It's called WIND ADSM Non-Stop with two plans (NS2 and NS7 for 2 and 7 days respectively).
You can activate it by sending NS 2 or NS 7 from your prepaid mobile to 19595.
You can get more info (in English) on their official page here:
WIND HELLAS