To the OP, I fail to understand how you find the quests unachievable? I've never played a space sim/game before now, and I've managed (so far!) to achieve each and every one. Where I'm not sure of how to go about something, I use an enquiring mind, look for information, and ask questions if I can't find the suitable answer on the/a forum.
I don't have a University degree, and have had various professions, all of them involving manual work. Add to that, nearly 60 years old, I should have a problem, but I don't. I tend to believe, that the reason I don't have a problem, is that the game is designed for all ages, and most levels of intelligence.
Please don't take my comments personally, they aren't meant or designed to be derogatory. As others have said, not every game is for everybody/not everyone's cup of tea, etc..
Good luck with your attempt to get your money back, but I think you may find it difficult if not impossible. I'm not a lawyer, but I would suspect you would have to prove that the game was miss advertised or not fit for purpose (or similar approaches).
Regards!