your q is difficult to understand because �2000 isn't an NHS charge. Since 2006, the most you will pay for NHS treatment in england (including crowns) is (currently) �198. 2 years ago it would have been cheaper than this.
Perhaps you dont live in england (sorry, i dont know the prices for scotland)
as to if they are garuntees, you need to ask the person who put them in. Also ask them why you paid so much!