Hello.

On Sunday I paid for a game on GOG and I don't have it in my library after the money was transferred to my account. I am asking for help in this matter. I reported the matter to GOG Support - no response.

Hello, You had a problem on Sunday and it's now only Tuesday. A reply after one week is a very speedy response time for GOG.

What's the status of the order in your orders history? If it's pending, in progress, or altogether missing, then there was probably some kind of payment issue and the order didn't go through. In this case, the money can be temporarily reserved by your bank and hasn't actually reached the seller.

If the order is complete, then try refreshing your account. While logged in with a web browser, open each link in a new tab and let it load fully. There won't be any confirmation message or anything. Just load your library page and check if the issue persists.
https://www.gog.com/account/refresh
https://www.gog.com/user/refresh

Just to eliminate any possibilities, did you buy the game directly on GOG.COM or did you use a 3rd party site?

I bought the game directly on GOG.COM

Here's a thought: Do you have a statement from your bank showing you paid for it?

One possibility is that they blocked the international purchase.