u/Cheap_Pineapple4229

My daughter bought her first property and there was just an old tap spindle screwed into the part circled. It originally would have had a fitting to change the water flow between the shower and the tap spout. None of the plumbing stores we have asked were able to help. Any suggestions please?

Edit: The brass plug between the two taps is screwed into a fitting similar to one for a tap spindle except the pipes from each tap come in either side and another pipe goes up to the shower head and another goes down to the chrome fitting blanking off where the bath spout should be.