wierd issues with safari on o2 UK site

[will lomas]

                hi on this page

http://shop.o2.co.uk/tariffs/18_months

try clicking any of the change bolt-on, links,a nd on my mac at least,  
nothing will happen. it is for a UK network. does it let anyone else  
change a bolt on add on for any of the tarrifs listed?
will