In my experience MailChimp customer service is hard to deal with and they don't really try to work with you even when you have a legitimate claim like you have. Also MailChimp will not give you any specific information about why you were shutdown other than just generic information.

I would suggestion just switching to another service. I've had better experience with https://mailgun.com/ because they will try to work with you more. They also have more options so if your industry is high risk, you can use your own IP addresses but still get the MailGun service.