I recently sold about 0.13 bitcoins (about 500 EUR) but the guy who bought it said that he would complete the payment in 2 hours, after he said that he confirmed the payment without doing it.
Now I don't know if release or not the Bitcoins, I didn't recieved nothing in my Visa card, but I'm still waiting.
What will happen if I don't release the bitcoins?
Please help me, thanks.
This is a fairly common occurance and it's really nothing to worry about. This is exactly why you use localbitcoins instead of dealing with the person that you're trading with directly, since you're protected by their escrow.
Ask them why they marked payment complete, even though they haven't paid.
Then, proceed to dispute the transaction if he does not respond. Do not release the coins.