I just bought the plugs that cover the licence plate holes. One of the threded nuts in the bumper that these lock in is loose and it pushes back into the bumper when you try and insert the plug. Has this happened to anyone else? Is there any soloution besides taking the bumper off to put this on. Thanks your help is appreciated

 

Notice how the hole has a thread inside? If you get the bolt that threads into that hole (from the licence plate bracket), carefully screw that into the hole and grab the bolt with pliars. You "might" be able to carefully yank the assembly so it locks down closer to the back side of the bumper surface. What you have behind there is a bracket that has 2 pressure fit tabs that hold a plastic pin that protrudes from the bumper. That bracket has possible slipped up the pin slightly or the pin has broken, parly or entirely.
The pin looks something like this as does the pressure clip. The following is from the grill attachment but looks similar to the thing you speak of:


If it won't pull any tighter using the method I posted, then you have another choice: With the bolt loosely screwed in, push the bracket back just enough to squeeze a little epoxy in and around the inner edge of the bumper hole, then pull the bracket back flush with the bumper hole and hold it there till the epoxy sets. Failing this, you'll have to remove the bumper.