If you're handy with a test light check your fuses, relays and if you are actually getting power to the bulbs in that order. The switches are a known fail point (and it does sound like yours may be knackered) but worth looking at the whole system in logical order.

The switches aren't brilliant but better than the first aftermarket versions of them years ago, though from the couple I have seen of late don't seem to sit as "tight" on the column as the OEM ones did from new. The commodore ones are different from what I remember of them.