Can I have my tooth bonding re-done again to match actual tooth shade? What are my options?

I had two very small chips in my two front teeth and went to a local dentist to have them fixed in May. However, the bonding color was yellow and darker than my actual tooth shade. The dentist said that he would re-do the bonding for free and mentioned the process was a quick fix. After bonding, it appears that a larger area has now been bonded, my teeth are thinner, tooth was improperly polished and the color does not match AGAIN. The bonding appears gray in pics is much worse than before.