I have bought multiple game keys off of G2A and I was satisfied until recently when I found out how easy it is to scam someone on there. You can only get a refund from G2A if you file a police report. Recently, I purchased a $42 game key for the seller to give me a faulty key, admit to it, and give me a second faulty key. Both keys had been used already and I sent him screenshots to prove it. He then started to laugh at me and accuse me of already using the key. I contacted Ubisoft support, the actual developers of the game, to see if the key was faulty or not and they stated that the key doesn't even exist. The seller is actually a scammer that has lied to me.
Unfortunately, I can't do much as a police report costs $50 or more to file a report and G2A will not do anything about it until I have an official police report turned in and stamped. Basically, I would have to spend more money in order to get my money back. If you buy from this place, keep in mind that you can be scammed very easily and G2A helps the scammers out rather than the customers.