Nothing herein contained shall affect rights of action arising, or litigation pending, or orders of the Federal Trade Commission issued and in effect or pending on review, based on section 13 of this title, prior to June 19, 1936: Provided, That where, prior to June 19, 1936, the Federal Trade Commission has issued an order requiring any person to cease and desist from a violation of section 13 of this title, and such order is pending on review or is in effect, either as issued or as affirmed or modified by a court of competent jurisdiction, and the Commission shall have reason to believe that such person has committed, used or carried on, since June 19, 1936, or is committing, using or carrying on, any act, practice or method in violation of any of the provisions of said section 13 of this title, it may reopen such original proceedings and may issue and serve upon such person its complaint, supplementary to the original complaint, stating its charges in that respect. Thereupon the same proceedings shall be had upon such supplementary complaint as provided in section 21 of this title. If upon such hearing the Commission shall be of the opinion that any act, practice, or method charged in said supplementary complaint has been committed, used, or carried on since June 19, 1936, or is being committed, used or carried on, in violation of said section 13 of this title