Unable to complete Reversal!!

Good Day, My wife sent money to a wrong person via banking app and she is devastated as her money can be reversed because they need the other person's approval. They have tried calling the other person and his phone is forever on voice mail and they tell her she must get a lawyer or something. This is frustrating as this money was meant to pay someone that she owed. This is frustrating for an unemployed person, Please assist her as she is now frustrated