Account Deactivated due to Switching Third Party Provider

I received an email from Amazon that my sellers account was deactivated due to being linked to an account that violated terms. When we got someone on the phone they explained it is because of ‘Company X’. Company X is linked to the third party that ran our store. That third party went out of business months ago and we have since hired a new third party that has been doing well since then. We changed logins, access, and permissions. Amazon old us on the phone that there is still a link to Company X that they are not allowed to disclose to us. Essentially, we need to keep submitting ‘guesses’ as to this link. We explained that we no longer use the original third party but this is not enough. We need to disassociate from the previous management company that no longer exists. Can anyone help with determining the link and how to reactivate our account?