Please (everyone), do an M-check on your bicycle regularly. No bike should get into this state unseen. You could die!

http://www.doitbycycle.com/maintenance/bikecheck.aspx

Original poster: stop riding your bike until you sort it out. And you need to learn some basic bicycle maintenance. Evans Cycles runs maintenance courses to help you learn the fundamentals. There is one TONIGHT, if you can book online and get to Leeds (use a bus or car, NOT your bike) at 5pm. They'll be able to show you what to do to keep your bike safe, and possibly even help you fix your current problem.

http://www.evanscycles.com/categorie...y-centre-store
http://www.evanscycles.com/products/...er-12-ec036670