I googled 'Competency Based Interview' and i was directed to this thread.
I've just had my interview; and Lexx87, it seems like we had the same experience with it! I was really caught out by some of the earlier questions about the company, as I thought my answers would have been adequate, but I was continually prompted to elaborate. Luckily I didn't have to make up any responses, but there were some lengthy delays in my answering when I struggled to think of examples.
I believe that everyone (who is human) will panic on these tests, and I'm almost certain that everyone will put the phone down thinking that they have failed!
If I could give any advice to anyone taking this style of interview it would be to firstly make sure that you are well aware of the company that you are applying for, do some good research. Secondly I would advice to make a list of as many key situations that you have been involved with as you can. By this I mean that you should try and pre-empt some of the questions that are going to be asked, but only jot down the situation and not the response. Basically this will allow you to 'blag' some of the questions with good solid examples minimising time taken to think about situations you have been involved in. Thirdly I would advise you to remain calm. (However if this involves 'Dutch Courage' then I would certainly remain on edge
Anyway, Lexx87, let us know how you got on! Good luck to anyone else who googles this thread.