could anyone please tell me where i`ll find the heater speed controller (rheostat??)...the mrs polo heater has only been working on full speed for a while now.................well about nine months

and today it`s give up the ghost completely so i think i`d best take a look before she freezes to death...or even worse.....asks to use my car instead.
if you can point me in the right direction before i start pulling the wrong bits of dashboard apart ???
it`s a 52 reg 1.4s with a/c ..if it makes any difference
thanks in advance..