Lorna
IAS should be able to provide a recording but Capita does not currently have the facilities.
You can, legally, record the interview yourself without notifying the assessor that you are doing so, most mobile phones have apps that can do this if a landline then as long as you can put the handset on speakerphone then you should be able to make a recording if you can't then you will need a specialist microphone to attach to the speaker.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
