shower tap

Good morning, Possibly a very basic question but have not com across this tap style before. New bathroom fitted a couple weeks ago. We have a Vellamo Cool Touch Thermostatic Rigid Riser Shower purchased through an online retailer. Noticed yesterday the cover of tap that diverts to either the...

Hi can anyone tell me what this is called? I have stripped our bath filler after it lost resistance on the handle to select taps or shower. the leg part has snapped off, I can't find a replacement that looks the same? thanks in advance