Hello had my 2G ceased on 1st August which i am ok with butgot sent a bill and have since been told my number is still active . Sim card was 3G and device was Sagem 2G . Have written to Optus ans on live chat and no help
As you say the SIM card is 3g and is still active and can be used in any phone which is capable of of connecting to to 3g. So if you don't want to use the SIM you must contact Optus to cancel.