If there is a trial, hearing, or arraignment date, if you can't resolve it before (e.g. with the City Coordinator), raise that issue at court or the hearing: if you did not violate any code, clearly, you cannot receive a summons; and even if you did violate a code, a failure to identify the one you violated should mean that this case is dismissed (though they could, in that even, re-notice you properly and try again) because without notice of the violation, you did not receive "due process": a chance to defend yourself (you cannot prepare to defend yourself against an unspecified violation).