Is ‘at all,’ which is used twice in the sentence, correctly used? Are ‘on the other hand,’ ‘by,’ and ‘such cases’ correctly used?

Is ‘at all,’ which is used twice in the sentence, correctly used? Are ‘on the other hand,’ ‘by,’ and ‘such cases’ correctly used?

Sad to say, Mr. and Mrs. Presley made no responses at all to the invitation by the teachers of their children to communicate with the school. On the other hand, Mr. and Mrs. Miller said that they’d talk to their children, but the talk yielded no results at all. Such cases, then, required the intervention of the school administrators.