They can look at you car and see if there are spots to get the tools in without drilling - usually there are. There ARE certain dents that can't be removed. I had 3 small dings removed from my M3. They didn't have to drill any holes. Two of them came out PERFECT. The third? The dumba$$ cracked the paint trying to get the dent out. Afterwards, he said he probably shouldn't have tried to remove that one because it was close to a crease in my fender flare.
The ding is smaller than a dime and the paint crack is only 1/4 inch but still ..... So ASK ahead of time whether there is ANY chance that it won't work.