Toyota Avensis 1.8 Auto. 2012 - Drivers side temperature control gone haywire 😱

[ToNo10]

Over the last few months it has become harder to select specific temperatures using the drivers side  ‘Temp’ knob.  It’s easy enough to select up to 16 degrees, but when temperature knob is turned UP to increase the heat, it flips to ‘Lo’.  Any ideas please, ‘Lo is not suitable for January in the U.K. ⛄️
 

thanks in anticipation.