Are they the only once in that premises! Well, they are just trying to warn the country that they won't tolerate none sense it something bad occurs. These are one of those things you'll always expect from the U.S

All you should be concerned now is on how to collect your money. As it was clearly pasted that the money is just a "caution fee". I won't conclude that its a scam, what I believe is that it wasn't properly man because there will be others with is same terrible case. If you have money I will advise you to get a lawyer and take them (JAMB) to the court of justice. Not only they will refund your money but they will also compensate you heavily.