This is just my experience. I got ripped off bad when I first joined the game. I went to WU on the first one. My bank denied the transaction at first. I did it online. Since it was denied by the bank, I call WU, and they said it was just a matter of the authorization request dropping off and then the money would be debited back into my bank. I didn't think much of it as that is how most hotels and many other transactions are. After 7 days, I called WU again to find out how come I still didn't have my money back. They informed me that it is policy to keep sending through the transaction until they do get authorization. On day five they did get it. Called my bank and there is nothing they could do.
For me MG just doesn't work at least out of the US if you try it online. I have found that if I take the same cash to Walmart and do the transaction it goes through in less than 5 minutes.