removal of inside door panel?

Hi, how do i remove the internal door panel from my 2004 citroen berlingo.I need to remove this because someone lent on the glass when it was 1/2 down and it now needs assistance by hand to go up or down.I have checked its tracking ok.I have removed the speaker but looking down the inside all i can see are plastic bottons(white) sat inside some plastic brackets(black),ive tried easing these but no joy.Many thanks

TrevB
February 2010