IKEA Customers Service interview questions

When I arrived at the store for the interview they left the candidates waiting something like 20 minutes, just before they throw us in a room full of strangers to resolve a case study (and we still didn't know the kind of vacancy available). They expect you to resolve a case with people speaking over each other trying to impress the HR. At the end of the process they give individual interviews, where you cannot change the idea they formed about you in the group assessment.