i have mono block taps on my washand basin, and when i put my ones on , as i can rember, there is a treaded bar about the same size as a biro, with long brass nut on it, you will see if you look up, under the sink, see if you can see just were the taps come through the sink on the inside" can you see the large washers they look like horseshoe" the two water pipes are going right into the taps through the silver horseshoe washers , well, the long treaded locknut bar with the brass nut is just sticking down just behind them two water pipes, get a light or mirror to see it , be carefull tighten it ,just turn the brass nut , one turn at a time till your happy , dont over do it , or you could shatter the sink , hope this helps mick..
mick, June 2008