(1) If a creditor makes a change in the terms of a revolving charge account or revolving loan account without complying with this section, any additional cost or charge to the consumer resulting from the change is an excess charge and subject to the remedies provided in this chapter.
(2) A creditor may change the terms of a revolving charge account or revolving loan account whether or not the change is authorized by prior agreement. The creditor shall give to the consumer written notice of such change not less than fifteen days prior to the effective date of such change.
(3) The notice provided for in this section is given to the debtor when mailed to him at the address used by the creditor for mailing periodic billing statements.
(4) Under no circumstances may a change under the provisions of this section be made so as to increase a sales finance charge or loan finance charge above that permitted by the appropriate provisions on sales finance charges or loan finance charges: Provided, That a creditor may apply a higher permitted sales finance charge or loan finance charge to the account balance or debt balance unpaid as of the date the change becomes effective.