I think your on a hiding to nothing but you may have a case if the shop didn't explain things to you properly and the paperwork doesn't either. It also begs the question why didn't you just go back to the Orange shop. But...
What was the sequence of events?
Its fairly typical that a new mobile comes with a new SIM even if your keeping the same number, especially if its something like a Blackberry as the services are tied to the SIM. Orange like to register a SIM to a particular phone as well.
Did the Blackberry come with a SIM?
Did it work when you got it and then stopped working or had it never worked?
Did you have another Orange mobile before the Blackberry and you wanted to keep the same number so put your old SIM into the new Blackberry?
Did the people in the Orange shop tell you it would come with a new SIM and you would need to register it before you could make calls?
What does the paperwork say that came with the Blackberry?