Amundsen+ 'phone book sort order.

I've searched high and low for how to do this, but nothing seems to work, so it's time to ask the cognoscenti here.

I have an iPhone 4 and the Amundsen+ radio in my Yeti. The 'phone book has uploaded OK, but when I try to use voice dial, it insists on my using "Call <Surname> <Christian Name>" order which is a pain in the neck. I just want to change the sort order - anyone would think it's a simple thing to do, but I can't manage it!

There was a post about this in one of the other forums here, but it doesn't seem to be applicable to the Yeti version (or I'm missing something).