Focus 2005 LX 115 TI Engine - Maxtrix Heater Issue

Anyone else experienced overheating cabin heater Matrix? Originally the Matrix was only luke warm and engine temperature hovered around 60 deg. I replaced the Thermostat housing and now the engine temperature hovers around 90 deg, so this seems normal although a little on the hot side. Water from the expansion tank runs into the thermostat housing and then through the oil cooler, out of the oil cooler and then through the cabin heater matrix which seems to get up to around 95 deg (very hot). It seems to me the cooled water from the radiator enters the thermostat housing and mixes through the engine before completing the cycle back through the oil cooler and then Matrix etc. So I thought maybe the thermostat is not opening/closing or allowing mixing as it should so I've replaced the thermostat housing for another new unit and fully flushed the radiator and hoses, but the problem remains. It seems strange that there doesn't appear to be a way of preventing the hot water from flowing into the cabin heater Matrix even when no call for cabin heating is being made (I can't seem to find any form of Matrix hot water bypass valve/circuit). Has anyone experienced the same problem and found a solution? Thanks, Steve