I had a quick phone interview and got invited to an assessment centre. The assessment centre contained of a presentation, one-on-one interview, virtual call centre scenario (computer call centre simulation with multiple choice answers) and we had some time to double-jack with an agent to get an idea of how the job is. While the phone interview was a probably five minutes in total, the assessment centre took over three hours.

Professional environment. Felt respected. Interviewers were polite and supportive to make me feel comfortable. Questions were the regular kind for call centre work. It's good to know as much as you can about the energy provider, all these things will help you in the interview.