I left Telstra clear in early June - I sold house I moved - I emailed them via their website and asked what to do with the modem- they never told me. Frankly I was a bit busy and had better things to do than hang on the phone trying to find out what do with it - I assumed that they were throw aways - as is often the case with cheap modems. 

Now 3.5 months later I have a bill for the modem! This is after months of them no cancelling the service, then 1/2 cancelling it - and then finally cancelling it!

I know they own the modem- but if they can't be bothered telling me what to do with it how much effort am I expected to undertake finding out what to do with it?  Obviously I'm not paying the bill - but is there somewhere I can appeal to - I find their attitude beyond arrogant . 

I left the modem in the house because the people who bought it were going to use TCL anyways - so its probably in use to this day!