Feeling my crowns crackling and clicking..?

3 years ago I got crowns on my front 2 teeth, I was getting annoyed with porcelain veneer as my black dead tooth kept showing through. But sometimes I feel a very subtle click and grating of the cement, when I press my tongue against them. I'm not pleased with the colour - in day light, they definitely look yellower than my natural teeth!! Should I get the original dentist to re-do them (a fight on my hands) or spend double the money and get them done again? How do I know they'll be any better?