New building floor heating not working.

My family recently moved into a newly built apartment. The underfloor heating is patchy, for example the whole living room area is cold, but recieves some heat from other areas.
The landlord is in denyal, claiming everything is okay.

I would like to get it independently tested. Has anyone been in this situation?

Have they even sent a technician to check? If not, perhaps reaching out to the mieterverband (tenant's association) could help.

I have spoken with the MV and they have directed me to a service that for CHF 150 per hour will review defects in flats and provide an objective report.
I've not used it yet, but it sounds like a good idea. My corporate landlord does not take issues seriously and seems to believe that they have no responsibility to their clients.

That's really unfortunate the MV suggests you put up your own money for such an inspection. I wonder who is then responsible if the company decides work needs to be done?