Cold tap drips when on but also when Hot is on

[ArnoldRimmer]

So here is the issue the right cold tap drips from the neck of the tap when it's turned on.. (not when off) however the neck of the cold tap also drips when the left (hot tap) is turned on... (The hot tap doesn't drip)

Now for the fun part these taps are in the wall there is no access to them or the piping other than what you see here in the picture there is also no way to isolate them the house water must be turned off at the main.

So if I turn it off mess around undoing these etc from the front and can't put it back together or make it worse I have no way of turning the water to the house back on

Has anyone worked on taps like this? and have any idea as to what is going on

 

[Madrab]

Are they 1/4 turn? If so probably need new ceramic valves, they do do that when they get worn and the water pressure is good.

If your not comfortable doing it then time to get a plumber in.

 

[ArnoldRimmer]

They are 1/2 turn, but to be fair they are probably full on by 1/4 do you know what the part looks like or maybe a video of replacing them?

 

[Madrab]