Was looking through CDT's (previously TTF - The Tyre Factory) website and came across this. Worked for me in Kingsbury - VIC this morning. Does mention 'at participating stores only', but not sure if there's a list. All it says is 'For any clarification, please contact your City Discount Tyres local retailer'.
Each voucher gets created upon click of the 'Download' from what I can tell, but they seem to be the saem each time.
Excludes Light Truck, 4WD and Luxury Vehicles.
I just buy my own tyre repair kit for around $15 and it does around 6 car tyre hole repairs. I've done one easily enough about 3 months ago and it works, no air escapes. True OzB style.