C# How to get complex shape components from an Element located via Fence/ElementAgenda

I have moved from V8 MDL to Connect c#. I'm trying to locate the best method to obtain all the complex shape component elements from the element retrieved via Fence/Agenda.

I've tried

el.ExposeChildren(ExposeChildrenReason.Query);

ChildElementCollection ceColl = el.GetChildren();

foreach(Element elSub in ceColl) ...

But it doesn't work. I think my foreach is the problem.

Any help appreciated.