2015 Land Rover Range Rover heater set point not accurate

What is your question?

Interior heater set point changes 1 hour after car is up to operating temperature. Car warms up properly to a 70 degree set point, but after approx 1 hour it blows colder air and the set point needs to be raised to approx 80 degrees for a comfortable level. It appears the colder air is coming from the dash vent locations.

What makes this problem better or worse?

increasing temp set point of the thermostat (up to 80 deg)

How long has your 2015 Land Rover Range Rover had this problem?

few months