(1) Where a period within which the act specified by the advertiser is to be accomplished has been fixed in the advertisement, the advertisement may not be withdrawn before the expiration of such period.
(2) Where of an unfixed period within which the act specified by the advertiser is to be performed, the advertiser may, until such time as a person has completely performed the specified act, withdraw the advertisement in the same manner in which it was originally effected.
(3) If the advertisement cannot be withdrawn in the same manner as the advertisement was originally effected, the withdrawal may be made in any other similar manner; provided, such withdrawal shall be effective only as against persons who have become aware thereof.