My husband telephonically said that he has given me three Talaaqs, and a letter stating this would follow.

Answer

The statement made by your husband to you telephonically is Talaaq Mughallazah. Three Talaaqs have come into effect. It matters not if he issues a letter or not. His statement that he has given you three Talaaq finally and irrevocably terminated the Nikah bond. Although it is sinful to issue three Talaaqs in a single statement, nevertheless, it is valid and the Nikah has ended. You are therefore to observe Iddat. The validity of the Talaaq is not dependent on your acceptance or rejection.

Sister, it is pointless to 'fight' for your marriage when the man does not want you. It is like flogging a dead horse. The marriage has already ended. No amount of fighting can bring about reconciliation in view of the administration of three Talaaqs.