it seems Coles decided to stop selling this coffee, which I have been buying for about 8 years now and since Woolworths had stopped years ago, I don't know where else I could buy it from
Available from FreshFood Services - $56.75 for Carton of 6 (More expensive then Coles though).
It seems available for me to order online in Western Melbourne. Perhaps visit a different store? Or contact your store and confirm if they have stopped selling it?
Also available from: https://www.unifour.com.au/Robert-Timms-Rich-Smooth-Freeze-D...
My local IGA (in Sydney) stocks it but in smaller sized packs than Coles (and higher unit cost of course)
Robert Timms Freeze Dried Rich & Smooth Instant Coffee
You can watch it out here https://mycoles.vip/