Looks to me like they've got the bumper hooked the wrong side of the bracket that its supposed to bolt on to.
If you have a look underneath and compare it to the same position on the opposite side of the bumper you might be able to see the metal bracket I'm on about.
My bumper looked the same as yours but I sorted it out when I removed it do some work on the rad.
Its pretty easy to get it wrong as the under tray attaches to the same metal bracket.
You (or they) need to undo the front of the undertray (only half dozen bolts) let it drop down then you should see the problem.