Oh... they are sending my original one back....
Annoyed at two things - they said they would send a replacement if they found the battery problem was independent of the break (so something has gone wrong in their checking process).
And secondly, they never offered me the option to pay the replacement fee.
The rep I spoke to also said she would be looking after this personally and tracking it for me.
Poor show. Really makes me want to go back to Apple with their customer service quality.