I here in Canada deal with the thing branded as Manfrotto, but the same product. I have broken leg clamp clips a few times, and have been able to buy replacements; I am one spare ahead at the moment.
The center column release lever on mine is designed, by pushing and turning half a turn, to be removable. It has a little allen key in it , and when removed, can be used to take off the centre column extension, or tighten the head mount. If you get a replacement, be sure to stretch the little spring that keeps it popping iff inadvertently so it does not do this again.