All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His Slave and Messenger.
In principle, it is the husband who has the power to divorce, although he can authorize the wife to divorce. However, scholars held different opinions concerning this issue and about whether or not it is restricted to the time of authorization, as well as about other matters that render the authorization invalid. Please refer to Fatwa 92334.
If the correspondence which you referred to in the question is from a legitimate Islamic authority which is entitled to decide such matters, then the query should be directed to that authority, and we cannot comment on it. If this was the first instance of divorce, the husband may revoke the divorce and take his wife back in marriage. However, since it is underlined in the question that the divorce was declared irrevocable (with minor separation), the husband cannot take his wife back in marriage without a new contract. Namely, the permission of the woman’s Wali (legal guardian) and the presence of witnesses are required, because the man has become a stranger to his ex-wife and he should be treated like any suitor who proposes to marry her. Please refer to Fatwa 82541 about the types of divorce.
We would like to point out that spouses should avoid being hasty with using divorce to solve their marital problems. Divorce should be a last resort. Couples should keenly use wisdom and strive to avoid problems in the first place. If problems occur, they should opt for legitimate Islamic methods for solving them. Please refer to Fatwa 85402 on the way to address the wife's recalcitrance and Fataawa 97217 and 89973 about how to deal with an abusive husband.
Allaah Knows best.