How to manage the customer when many mistakes from your side?

Listen and sympathize on what ever your customer is telling you, be on his/her foot so you can understand what does it feels or what is the effect of your mistakes. Then apologize for your mistake and try to solve it, do certain action that can bring him/her back offer something or guarantee something. Lastly THANK him/her for telling the truth of a bad experience this may be negative but on the other side it will be your opportunity to improve more and never do the same thing again.