If you have an account already with no previous refunds, you can do it on that one.
Buy your product, CD KEY ONLY from a saler with a good reputation, the more sales he has, the better. Make sure G2A Shield is active, you pay a dollar or two more but it increases your chances of refunds dramatically. No steam gifts, get a key.
Redeem your product.
Go to helpdesk chat and tell them the code does not work. Use your brains here, it’s not rocket science, you just tell them the cd key was invalid.
They will refund you your money and you will be able to take it off your G2A wallet in two weeks or you can use it to buy an other game rather immediately