After going through the archives to determine why I was getting hot air through the defrost and the footwell, even when the temperature dials were set to OFF. I decided to take out the heater valve. I took the heater valve apart and found a small chunk of plastic, from a broken nipple on the aux. water pump (which I just replaced) I also found two broken guides (see pic) for the plunging shut off valves. I dont think the plastic chunk would have caused this as both sides of the guides were broken.

Just another thing to check if your heating system is acting up.

Cheers