Optus has been slashing broadband speeds to half the level advertised for customers who exceed their monthly download allowance.

Customers of Optus's "Naked" ADSL broadband plans have their internet speeds throttled down to 64kbps for the rest of the month once they exceed their 7GB, 15GB or 30GB monthly allowance.

This is half the speed of 128kbps that is listed in the terms and conditions published on the Optus website and about the same speed offered by ancient dial-up modems.