Orange have them on contract ... or buy one from another source (usually US) I had the same problem and gave up on O2 (my prefered carrier 2nd choice Voda but I will not use others due to lack of coverage) I ought one (only buy a NEW UNUSED one much less hassel!) And I unlocked it for �twentyfivepounds...
Fantastic ..really glad I bought NEW and bought the 8320 (it's the only one for me)