Classifieds not seperating Parent and sub categories.

I have 3 Parent categories that have simular sub categories. The subcategories show up one after the other when someone tries to list.

Exampl:

Copmuter<<<<<Sub Category

Computer<<<<<Sub Category

Computer<<<<<Sub Category

It should be more like

Service offered <<<<Parent

Computer <<<<<Sub Category

Help needed <<<<Parent

Computer <<<<<Sub Category

Temp Work <<<<Parent

Computer <<<<<Sub Category