Sir/Madame I don’t want to mispronounce your name can you tell me how you say it, they normally says one of the following..
1. It’s pronounced ….
2. You try
3. Call me by my first name.

1. I will repeat and write now phonetically and tell the other crew serving in that cabin.
2. I will have a go hopefully getting it right, the passenger will correct me and I will repeat the above.
3. Ask if they would be liked to be address by all the crew by that name.