If you want to complain, you can only go to the website of MSC, check the email address of their headquarters and send an email to their headquarters to complain. At home, no one cares about them, because these shipping regulations are the shipping company's own rules, and there is no industry standard. But if you complain to their headquarters, there should be feedback, but it may not be solved, but there is no way but to try. There may be some problems that they can't solve because they involve foreign agents and customs.
I suggest you try not to get on MSC's boat in the future and let them go bankrupt in China, but his freight rate is low and many customers have to leave. There is really no way!