I'm afraid there is an extremely high likelihood that you have been scammed, by a predatory journal or just a run of the mill scammer.
The first red flag is the requested use of Western Union. Any payment requested by Western Union is highly suspect - I have never once encountered a legitimate use of Western Union or Money Gram other than to personally send gift money to a family member personally known to you, and never as a payment for anything. I've never heard of any legitimate publisher of any kind using either service.
The next red flag follows from the first, about the "mailing address of the publication fees" being wrong. They are trying to get you to pay them again, and will likely come up with some nonsense story about how you can get the other money refunded but they need proper payment right away to the "correct" address or they won't be able to publish your article (or some other lie). They will do this over and over again, so long as you keep paying them money, and you will get nothing worthwhile in exchange.
From the sound of it, you have selected an illegitimate source to try to get a publication, and they will attempt to get as much money as they can from you. Regardless of what you pay, the most you will get is a meaningless "publication" in a predatory journal, which may not even exist and even if it is every put online it may just vanish overnight. From the sounds of their trying to shake you down for additional money, I suspect they won't even give you a fake publication, they'll just disappear and stop responding.
I rather doubt you will get any of your money back, but I would suggest if at all possible to back out of the deal, request a refund, withdraw the article by any 'official' means (I doubt they have any true official way to contact them by certified mail, of course), etc. Cut your losses, don't pay them any more money, try to avoid losing your work (by being technically published and not easily publishable in a reputable place), and spend extra time researching any potential publisher in more depth before submitting your work in the future.