Matrix heater problems , coolant .

2016 Octavia first service they noticed the coolant being an odd colour . Since then I have had numerous issues with coolant leaking , water pumps changed , heater matrix is now the third installed . Basically since new the car has consistently had issues and is off the road frequently. Skoda dealer is struggling to find where the problem is coming from . The most recent issue was a full new heating system installed which took 5 days at garage , the car lasted 2 days and the same issue was back . Feels like they are going round in circles .