merc190ee

I am trying to remove a sunroof headliner from an electric sunroof on a 1992 190e. I have a problem removing it, the clips seem to be stubborn as hell. I've read how to do it : open 1/3 of the sunroof then pull it down as the clips are more in the front. I tried pulling the headliner down with a lot of force - luckily I didn't break anything - and the headliner remained on. I used some trim removal prying tools, but tools are just bending and do no good. Any ideas what tools should I be using for these super stubborn clips? Maybe some good diy solution?