I'm surprised that c/s don't transfer you.
Failing that, you can wait until office hours and ring the switchboard and ask for dept you are after.
You may also get a better deal if you threaten to leave and take your number to another network in which case ask for Online Contract PAC (Port Authorising Code) code Dept because you wish to leave o2.
You may also wish to visit relevant MSE articles
here and
here.
Also, if you aren't that bothered about a new handset then o2 Online are doing a double mins & text SIM-only contract which is very good value with only a 30day minimum contract only. For more info visit
here.