If your Thermostats or app are heating up the wrong zone, the simplest solution is to swap around each Thermostat.
If you have wireless Thermostats, press firmly on the top of the Thermostat and lift off the bottom edge to detach it from the backplate. To reattach the Thermostats, hook on the top edge, and press firmly on the bottom edge.
If you have wired Thermostats, find a small, thin hole on the underside of the Thermostat. Gently insert a flathead screwdriver into that hole until the Thermostat clicks off the backplate. To reattach the Thermostats, hook on the top edge, and press firmly on the bottom edge.
Check the Thermostats are now heating the correct zones, either using the Thermostats themselves of the Passiv app. If you are still experience problems, please reach out to your installer.