I have sold clothes before, indicating that I will directly ignore such customers.

If you can't be the boss, you can ask the boss directly.

Besides, even if he bought such a question in the mall, it is impossible to change it for him!

It's not your fault. You don't have to feel guilty or anything! Explain the problem directly to him. If he is still struggling, you can ask the boss to come forward (after all, the right to work is not that big)