As far as I know, all you need to do is press and hold the control key and click with the left mouse button while holding the control key. That's how it's done. If that still doesn't work, you've found a bug.

The only other method I can think of is to use the hide unselected feature. Select the area you want to select (the face part as an example) in face mode and click the "hide unselected" button. This hides everything else so it can't be selected (only the head part is shown). Narrow your selection down by selecting the parts you want to select (such as just the eyes). Click the hide unselected button again and keep repeating until you have what you need. This is the only other alternative that I know of.