Urgent Help with parent, child categories and entries

I have this website http://www.eprep.com.au/products

I am showing the top level categories or parents, that works nicely.

When click on EPREP Sample Preparation Work Station that will show the entry assigned to that category, that works nicely.

However when click on EPREP Accessories that is to show the second/child categories, not entries until you click on one of those categories.

So basically I am asking is it possible to show entries under parent categories and then show child categories under parent, then click on child to show entries. I can’t have an entries seen under parent categories that have child categories.

I hope that makes sense.

I urgently need assistance with this.