9:00– 18:00。 According to McDonald's official website, McDonald's has a 24-hour customer service hotline, which works from 9 am to 6 pm. Therefore, the opening hours of McDonald's 24-hour complaint telephone are 9: 00–18: 00 every day. McDonald's has been ranked in the top of BrandZ's list of the most valuable brands in the world for 13 years in a row. In 2020, McDonald's ranked ninth in the list, and it is the only catering service enterprise among the top ten, with a brand value exceeding 19338+0 billion US dollars.