Mk 4 sat/nav upgrade in my 03 range rover

Hi people, need a little help with a slight hitch. I fitted a sat/nav upgrade from the Mk3 to the Mk4 unit, but on the main menu screen does not allow for auxilary heating, only auxilary ventilation, has anyone come across this. I was told by the supplier that a simple re-program was all it needs, but my main dealer has never heard of such an up-grade and therefore cannot help me.
Thanks for any help you have