Hi Ryhs dont buy the current shape one as there are huge issues with leaking roofs. The new facelifted one is in production now and uses the volvo seals so it shouldn't leak. Many people are taking there old ones back and getting full refunds.
If your mum doesn't mind taking the car back to get the better seals fitted on the older shape one she could save around £3500 on the cc3.

If you need any assistance let me know as i work for ford.

Simon