When my heater played up l;ast month, the first thing I did was to buy a new FSR and try that - but it wasn't the problem. The evaporator had leaked all over the heater motor and compeltely lunched it.

So, I have a brand-new genuine LR FSR (final stage resistor) sitting in the garage, possible even still in it's box, which I bought about 4-5 weeks ago and which has only ever been test-connected to the car to see what the problme was. IIRC it cost me about £41 in VAT. Anyone want it delivered for, say, £30? (It's heavy so it'll probably cost a fiver in postage).