I get what you're trying to pick at, and once again the most I can offer as a response in terms of your account data being deleted is "freak accident" or alternatively there may be another reason why they can't or don't want to restore the account which is why they're now concluding that it doesn't exist or never did (truthfully, you were probably talking to different people and they're spinning a different story while ultimately trying to tell you they can't do it for whatever reason). That is still to the discretion of whoever is holding the actual data itself, which from my limited knowledge doesn't always happen to be Nutaku (and likely can't be for Nutaku to advertise that particular game in the first place by contractual obligation).

For the record, just about every game I've played that stores its data online comes with a ToS that says it effectively owns your account data, regardless of how much money you put into it, and that they can change it, restrict it, delete it, etc. however they please whenever they want. Of course, almost no game calls this particular card and most devs hope to only have to use it as an explanation if the game itself gets shut down, but it doesn't change the fact that they will use it if you want to push this any harder.

Yes, it sucks pretty bad to realize your hard-earned money just vanished into oblivion and no one can properly explain the story (because no one was looking to begin with) but I think that's a lesson in itself. I'd hold it against the game and not Nutaku though, just saying. At best, you'd be able to ask Nutaku for some credit back to your account seeing as whatever it paid for stopped existing without valid explanation but as there doesn't appear to even be a way to get a hold of whoever manages the financial bit of the site itself, that option is pretty difficult too. Your transaction data probably still exists and can be traced, just a matter of who you'd have to contact to get that sorted out and more likely than not you'll contact the wrong person.

Though it's a shot in the dark, you could try sending an email directly to support@nutaku.com. In the distant past I've gotten replies from sub-branches of the site for certain games asking that I contact them directly with technical concerns towards whatever games they were dealing with. It might get you closer, can't say, probably will end without result, but seeing as you have little to lose...

Finally, Google Play, and everything related to it, is a golden standard. Games and apps that affiliate with the google brand work extra hard to make sure you don't get unreasonably screwed over, angry, and very loud to the point that someone genuinely important takes notice. It's a lovely system but I can't say that it applies here.