Bathroom Tap Leak - Please help!

I have a tap in my bathroom which is attached to the mirror. It has been leaking for the last couple of weeks.

I have used various sealants but nothing appears to be helping.

I have attached a picture which shows where the leak is coming from, which is just under the metal part which adjusts up and down.

Any help would be much appreciated.

No amount of sealant is going to work. If you do, it will just reroute to the drywall. You will have to get the proper repair parts and rebuild the pieces.

I suggest removing the chrome cover on the valve and replace the cartridge assembly. Not sure what that is. if you can remove it, might be able to tell you what it is. If you don't think you can do it call someone who can.

Here's what might happen. If it's a odd custom type valve, the plumber is probably not going to carry a replacement part. Hopefully he can Identify it.
Call around and make sure you find someone that has a good chance of solving the problem before you hire him.

Looks like it may be a kholer