I migrated over to the 200GB Mobile Broadband plan just over a month ago from VividWireless where I was paying $70, so why am I being charged the same amount when the plan I am on is being advertised for $65?
Did you get a new modem and if you did is there any chance they are charging you $5 for it? This $0 up front modem charge may be the culprit if that's the case.
What did you agree to when you moved over? If they offered you a $70 plan then that's why you're being charged $70.
You can always discuss your options with Optus direct though