Need some help!

My current Navi600 has died. Wonít switch on.
Vx have told me they will code a replacement into my car (at a cost of £260ish!!)

They also said I need to have the new unit divorced from the old car.
Is this true? Or can it be done once the unit has been removed from the car?

Do I have any other options with a dead Navi600?
I looked at aftermarket options, but yet all say they canít be fitted to a Naviíd vehicle.

Iím stuck and canít afford a lot to get this sorted.
Any help appreciated - thanks.