Couple of months ago, I was looking for the weather forecast on my local News channel [dress according to the weather, lol], and they said that the Dent remover don't always work, it only works on certain types of dent. I didn't watch the whole thing, I just remember them saying it. I didn't help much, but just to let you know that it doesn't always work.
I think, they just work on round dents, in the center where it doesn't take much force to get them out.
If you do use it, be carefull; don't want to mess that paint up again.