So the preparation for two indoor units and thus also two outdoor units costs us about €1300.
Did you want two outdoor units for the 2 indoor units as well, or was it offered to you?
We have 5 indoor units and one outdoor unit... I wouldn’t know why you would use two outdoor units (the distances outside are too long, which almost never happens in a single-family house).
Can you explain the services for that in more detail? What needs to be done here? What is needed for preparation?
And where would you have installed the outdoor units? I wonder if you can really strap them onto the roof with such a low roof pitch.
You need a double refrigerant line and power supply from each indoor unit to the outdoor unit (possibly also an extra BUS cable but that depends on the manufacturer). You should also think about how to dispose of the condensate (where to, with or without a pump).
You can also "strap" units onto the roof, they just have to be properly secured. However, there will be a hefty surcharge since such an outdoor unit doesn’t weigh only 5 kg.