Maybe you could try and search it on Allkeyshop, it's a multi-shop search engine, search for the season pass and see if some shop has a GOG key for it on sale, then check if you can use your card there.

No offense, but that's the worst possible thing they could do. A lot of the keys from key resellers get revoked, especially lately (it seems), so OP would be taking a chance that something happens to the expansion pass between now and when it's released.

Maybe you'll have some luck on the Humble Store (it's a GOG key).

I'm on the phone so it's hard to look it up, but one greek user reported a Paypal workaround. You need two Paypal accounts, one with your real address and credit card and one with no card attached. The you'd have to transfer money to your second account from the one with the card. You can then use the second account to buy stuff. I hope i haven't missed anything.

yeah i heard about that paypal trick but it doesn't work for me.

They don't sell the season pass on keysites.I'll try humblebundle and we'll see.

Someone told me that humble store worked for them so this could be it.

I bought myself several times, Kinguin and G2A as final shops searched via Allkeyshop, and everything was ok. Sure, it's better if you rely on these shops (they provide purchase insurance) but you can also check other shops rating before you go and buy.
Unfortunately seems like OP need some way to bypass his payment system issues, so he'll probably have to rely on key resellers, maybe Humblebundle (if it offers GOG key(s) he's looking for) could be a valid try.

i bought MGS5+GZ from a relatively unknown keystore and it worked fine(instant gaming)

I did a quick search, unfortunately on Allkeyshop for "season pass" there are only the Steam and GOG official links (no resellers), but I see there's a 19,99€ expansion GOG key, you could maybe check that shop carefully and, if it's reliable, go for a separate purchase for different dlc.
By the way, Italy here, I hope things will get better in Greece... and in my country as well! :)
Take care.

And G2A is exactly the place where lots of people got their Witcher 3 key that got invalidated later, because it was bought on GOG with stolen credit card data...

Seriously, stop recommending key reseller sites. If a game costs 45 bucks on the own store of the developer (or its sister company) and someone sells keys for 15 or 20 bucks, then it's NOT A LEGIT OFFER! Common sense. Really. Better pirate the games if you don't want to pay full price for them. This would still suck, but at least you wouldn't support criminals with your money then.

^^thanks

I tried the humble store and it says that my order is being reviewed so i am guessing it will most likely not work.

I'll try it a couple more times if it fails.

edit:

The only reason i even looked at key sites is because i couldn't buy MGS5 on steam.
It was not my first choice but i had to risk it.Hopefully it was not a stolen key or anything.

Since you said above that Amazon worked for you, you could also try buying a GOG key from too, in case Humble Store fails on you. Also, [url=http://www.amazon.de/Witcher-Wild-Hunt-Expansion-GOG-com/dp/B00XO24FHA/ref=sr_1_3?ie=UTF8&qid=1442135623&sr=8-3&keywords=Witcher+3]from Amazon.de if it makes a difference.

I can only tell about my experience, I bought on G2A and Kinguin multiple times and not form people selling on them, just shops' selected and direct products, and it was fine. You speak of commons sense, and I aggree, so if i see -example- a brazilian seller offering a rus key for 40% of the normal price I stay away from it, but if it's a direct shop offer and can spare few bucks I conbsider it, not to mention that G2A offer a purchase insurance -which I always used- to protect buyer.
I usually wait for GOG, Steam, Humblebundle sales and buy on them, but sometime I go for other shops and I never had problems.
And, again, I think you miss the OP main problem: he wants to buy but there's a problem doing online payment for people living in Greece, so, unless he has a trusted friend in a foreign country to buy for him or something change, he will be forced to try on different shops.
All I suggested was to try and search on them as well if normal options were impossible to OP.

Well, you're in a special situation with those stupid capital controls, but... Yeah, especially with Witcher GOG keys there seems to be a very high chance that they were bought with stolen credit cards. That's why you can't purchase this game as a gift on GOG anymore (and why the GOG season pass isn't available on those sites, since the gift purchase was disabled from day 1).

I know that it sucks if you try to be honest and pay for something, but your Government doesn't allow it because of *burp*. Just be aware that the stuff you buy from key resellers could be just as legitimate as a copy from this Pirate Bay-thingy. And in the worst case you give your money to some criminal scammer who stole someone else's money.
That alone should tell you how legit those keys are. Have you ever bought a "purchase insurance" in the supermarket, just in case the police takes away the food you bought, because someone stole it and sold it to you?

No, I don't. I just wanted to point out that something doesn't become legit just because you pay for it. Yes, it sucks not to be able to buy a game. But it sucks even more to give your money to criminals and to get an invalidated key in return.

Guys i bought it from amazon.uk and it worked! ;)

I got the code instantly and ended up paying less since 15 pounds is like 20 euros.

How did i not think of that?

Now if only i could find a way to buy the dlc for DAI on origin......