How can you handle complaints in a proper manner?

We should have a protocol to deal with Complaints(customer) : as per the following :

1. LISTEN to their words, rationale, and according to the situation2. ASK a deeper question to understand intent3. DESIGN a solution that bridges the gap4. Take ACCOUNTABILITY for making a next step happen5. THANK the customer after fixing 'it'

Every organisation that deals with the public receives complaints from time to time about its activities. Complaints are inevitable and have to be managed.

1. Apologise for their inconvenience

2. Remain calm and positive

3. Allow the Customer to Speak

4. Listen without interrupting

5. Respect the customer

6. Put yourself in your Customer’s Position

7. Take Responsibility to Resolve a customers problem

8. Ask the Customer for an Appropriate Solution

9. Follow Up the Problems with Customers

10. Thank them

A client called and said he got a food born illness eating at our establishment. I should mention that the dish he thinks made him sick was prepared the same day and the restaurannt follows all rules of food safety. He hadnt been to the doctor and he is just following a hunch that what he ate at the restaurant was what made him sick. I explained to him that the restaurant follows very strictly the rules of food safety . . He asked me what we were going to do to make it up to him and i asked him what would he like us to do but he just got very annoyed and hung up on me. I dont know if there was a better way to handle it for a future incident. Let me know what you think.