I'm trying to upgrade my Ubuntu release from 12.10 to 13.04, having successfully upgraded to 12.10 yesterday. With the intention of then moving to 13.10.

I am up to date with other software updates.

Using the Update Manager I am offered to upgrade the release, but this is offering an upgrade to 13.10 instead of the expected 13.04.

When selecting upgrade this does in fact attempt to upgrade to 13.10 'Saucy', the application tells me off for doing so, rightly so, and sends me away.

Any ideas how I can upgrade to 13.04 firstly?