Mobile broadband connects to wrong USB device

[Ben <ben benjamin it>]

Hello, I have a Dell Mini which uses a 5530 mobile wireless card. This
works fine with wvdial etc. When I try to add a new wireless broadband
connection using Network Manager, I select Vodafone (as they are the
provider), and then when I try to connect to it, I can see in the top
right where the Network Manager icon is trying to connect, if I move my
mouse over it I can see that it says it's trying to connect to USB0,
however the wireless card is actually using USB4.

So, my question is, how can I get behind the scenes of the new network
connection to make it try to connect to USB4 (/dev/ttyUSB4) instead of
USB0? There doesn't seem to be anything of interest in my ~/.gconf/* dirs.

Thanks,
Ben.