adjust hinges on upvc door?

My upvc back door is not sitting snug up to the frame and so a draught is getting through all around it. I have looked at the hinges ( there are four) and there are plastic stoppers on the top and bottom but when I take these out there is a metal pin inside (but no allen key holes). On the internal door side to the hinges there is a small oblong shaped plastic cover with an indented cross shape at the bottom. Is this where I can adjust the hinges and what tools do I need?