Freelander 2 and tow bars

We are returning to caravanning have bought 2007 Freelander 2 and waiting to collect our caravan.  I want to fit a towbar to my freelander but it has rear parking sensors which cannot be switched on from the dashboard.  I have been told that a Landrover dealers are the only people able to deactivate the sensors.  Has anyone experienced this. Landrover want £800plus to fit towbar and electrics.