probably too late but here goes....
Customers with lost/stolen and faulty handset are unable to complete SIM swap using the above methods.
the code that is asked to complete the activation is a four digit random code sent via sms to the number, so if the number is barred you cannot do it. 0000 is the default pin code of the new sim.
Also if the sim card was provided by an O2 store they have to activate and then 202 or chat can remove the bars. Customer services will not activate sim cards that have not been posted by O2.
So it's either back to the store or 202 will order a sim. If it was sent by o2 then like it was mentioned it's a quick phone call or web chat will do it
Hope this helps. 
