In the case of an unjust suspension (or at least what a user considers to be an unjust suspension), it seems that better way than to bring this up on meta would be contact the SE team using the contact form or by writing an email to [email protected].
See, for example, an answer to the meta.SO question: http://meta.stackoverflow.com/questions/165359/where-i-can-complain-about-an-unfair-account-suspension/165360#165360. This solution was also suggested to you in a similar discussion on meta.MSE.
EDIT: As François G. Dorais points out in his comment below, another way to dispute a suspension is to contact the MathOverflow moderators.