Help fixing a tap?

My cold tap doesn't work - it just runs a dribble when turned on. When off, its off.
Do I need to change a washer? Maybe I need to replace the tap?
I got this far (see photo) however, when I use my adjustable wrench to try and turn the brass bit off, the tap body just moves with it....
Photo
http://picpaste.com/P1070566-zBtfxp6N.JPG
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I cant get the brass bit off (still). If I buy a new tap, will I still have to remove that brass bit? May just replace the whole thing.
Under the wash basin: Wide view:
http://picpaste.com/P1070576-qk3Ijcyv.JPG
Closer:
http://picpaste.com/P1070577-MPPxRLEC.JPG
Don't know why I put these here. Maybe someone's got another tip for me.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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