From our end you can check your usage via My Account.
Prepaid services will show the last 30 days, but billed services will have itemised records on your previous invoices.
Hope this helps!
I think post paid invoices only itemise mobile call details. SMS are bundled into a single line item (Quantity: 125). Presumably to save paper?
Perhaps another reason to recommend pre-paid (along with no fee for going over a data limit and unused data rolls over to next month)