I had a plumber in recently to service my boiler and while he was here I asked if he could change the washers on my leaky bath tap as it's driving me nuts. He was really nice & showed me how to take the tap apart so I could do it myself next time. I thought that'd be the end of it but the bloody thing STILL drips! It also has a slightly larger water leak each time the boiler timer clicks on to heat the water. I have no idea what's going on. Plumber man says the tap should be fine but it isn't. We're switching to a water meter soon & I need this sorted. The water that drips is neither hot nor cold. Please help.