Update: Been many weeks and somehow the heat didn’t seem too back and seems to have got better over time but wanted to see what it could be to know better. The dash temp looked pretty normal too now.
Today visited the garage and started a deeper enquiry for fault finding. Was advised to undo both coolant entry points on the firewall to the heater matrix to see if there was blockage / buildup of crap. All looks good with a pressure garden hose flush.
Then in the cab looked at the heater climate control switches. Cold to hot slider that opens up the reverent parts in and under the dash. At this point selecting hot reverted back to blowing cold again like before for some reason.
On the diagram online looks like 4 different parts that the failure to open the heat to the cab could be.
Note: At this point he rear heater switch was turned on and hot air works towards the back ok.
Drivers side left side under the dash clearly could see the mechanism moving up and down. Also passenger side bottom under dash too looks good.
At this point a easy fix was hard to find and my cousin at the garage said he will look into which remaining two is the one that could be at fault.
Very uncommon this is but not something that fails.
Any ideas welcomed… thanks