Which new rear Cabriolet Bumper?

Hi - I was waiting in roadworks traffic on Tues morning when a kid who had been driving for 2 weeks skidded into the back of my A4 Cabriolet.

His car was an R reg Peugeot 106 and has been written off!
http://www.astwood.co.uk/jay/accident4mar.jpg

Sorry, no pictures of my car as the back looks exactly the same as it did before! The damage was just to the armored inside of the bumper, a bit of internal bodywork and a small nick in the bumper and the tailgate!

The only real visible damage is at the front of the car, under the bumper where a little wind deflector trim has come loose from me moving up towards the grass verge to avoid his line of fire!

So - its still about £900 worth of damage to my car because of the internal bits' costs.

I will need a replacement Bumper. But I was wondering whether to have an alternative rear bumper.

http://www.astwood.co.uk/jay/S4rear.jpg
The 06 onwards A4 bumper, the rear bumper is more bulgy around the black part between the exhausts. Is this the only other option as I think the Cabs' bumpers are different to the Saloons?

Cheers