What to do when you want to change a two hole tap basin to a one hole tap?
The pipes are separate for hot and cold water, is there a connector we can buy from a DIY shop in order to link the two existing pipes and turning it into one to fix a mixer tap ?

If I get this question right... you can install a sink hole cover (see pics.) in 1 hole and then use the other for your faucet. Or you could install a soap dispenser (see other pic.) in one and the faucet in other.

The fittings will depend on your faucet and the type of piping under your sink now.

And now, you don't want to hook pipes together underneath...right? That would be a cross connection between hot and cold pipes (usually a bad thing). You want to hook both pipes to the faucet (which is a mixing valve in a way... huh?)... yes? Or is this something different?

Get back to me with information... Thanks... Mark