I have an exafill bath filler waste, which I am fitting to a new bath. I have fitted the filler / waste part but i am having trouble with how to fit the actual plug. The plug has a screw in the plastic part that goes into the plug hole and when the knob is turned the cable moves a metal bar in the bath waste which rises or lowers. The trouble is how does the metal bar attach to the screw or is just a manual system where by you push the plug into the hole and when you need it to drain you turn the knob? Has anyone fitted one before and have you any advice? Thanks in advance for your assistance.