Uneven crown surface, should dentist replace free including his time? Can I expect to get what I paid for without paying again?

6 months ago a private dentist replaced my two top front crowns, they were over 10 years old and had some metal showing near gum line. A few months later I initially felt and then noticed an uneven surface on both crowns, more on right. I have a small overbite, dark posts were fitted 30 years ago. I imagine the error occurred when they tried reducing the bulk without the dark posts showing through &nicked the surface. NHS dentist also noticed poor gum line, he though they were several years old