Gutted to hear and hope that you get resolution sooner rather than later, be that insurance or the car returned.
Just to clarify the Advanced key thing is a red herring, it's got nothing to do with it in this case. The issue is, as I understand it, that a key is programmable via the OBD port, which then means the car can be started with that key - advanced or standard. I believe the confusion arises because cars with an "old" style ignition barrel don't have this problem because you have to have a physical key cut the same way. The press releases refer to these types of car that have the advanced key as an option, as you no longer need to put a key in the ignition barrel they become susceptible to this type of theft. The A4/5 (and I would assume 6,7 and 8?) have a sufficiently "smart" key as standard to make them open to the programming attack.