Well here is a story, I am not obliged to wait on the retailer sending a console off to MS for repair ( having had numerous 360's red ring and getting a straight over the counter replacement every time ) and when my PS3 40gig croaked it I was given a brand new 80gig model as they had no 40gig models left.
The retailer is responsible to give a replacement of equal value so even if the elite is reduced until all remaining stock is cleared and when I go to the retailer when I am sure they have no stock left in store, my receipt for £200 elite will entitle me to a replacement slim of the same value.
When was your original receipt?
As that's one factor.
Secondly, the retailer is under no obligation to give you a new console exchange. Their priority is a repair, within reasonable time. So it will all be down to the individual retailer as to whether in your case, they will swap you out for a brand new model, or whether they will simply offer to repair it, as it's no longer a straight swap.