Squeeze transitioned to LTS a couple of years (or so) ago.  Just in
last week or two the LTS terminated and Squeeze was archived.  It is
no longer supported by Debian or the LTS team, nor is it present on
Debian servers.

To get old packages use snapshot.debian.org.

E.g. Squeeze was still present on the 1st March this year so using
that date I suggest pointing apt at:

http://snapshot.debian.org/archive/debian/20160301T103342Z

(It is possible there might be some final Squeeze LTS updates since
then before it was archived.  I am not sure of the exact date support
terminated.)

Cheers
Michael.

Thanks Michael, that was very informative and helpful.  I figure there might be someway of doing this.

The texlive was pretty old so in the end, I decided to remove the texlive packages and just install texlive in /opt on the server.

That way I'll have all the packages upto date.

Chris