Lost C5 installation disk


I am upgrading my DAW and have discovered that I’ve lost one of my Cubase 5 installation disks which I’ll need to re-install C5 on my new machine.
Could anyone please advise how I might go about requesting a replacement and how much this would cost?
'My Steinberg" directs me to yamaha’s Australian website http://www.yamaha.com.au - not very specific…

Alternatively, might also be a good time to upgrade to C7 - again, any suggestions on the upgrade price and how to do this locally?

Much appreciated!