The C&S glitch that shows NT suburbs is a known issue that they have been "working" on for some time now.

There is an easy workaround that works most of the time. When you press search and it shows the list of NT suburbs, simply remove the suburb/city entered altogether and just make sure the Postcode is correct, then press the search button.

It will show a list of the suburbs for the postcode entered, so then just select the suburb and all will be fine.