Thanks for the help guys, I got stuck into it and pulled the dash out. The problem ended up being twofold - the thread on the heater dial had stripped and the whole switch moved rather thatn the wheel on the rear. I fixed that by adding a washer and then the locking nut. The ither problem was the control gate under the bonnet near the firewall where 4 heater hoses enter. The gate was very stiff. I replaced that and bugger me, the car has hot air!!!!
Cheers and thanks.......