(a) for any violation of the requirements of this chapter if within sixty days after discovering the violation, and before an action is filed against a merchant or written notice of the violation is received from the consumer, the merchant notifies the consumer of the violation and makes whatever adjustments to the account of the consumer as are necessary to assure that the consumer will not be required to pay an amount in excess of the amounts actually disclosed;
(b) under this chapter for any act done or omitted in good-faith conformity with any rule, regulation, interpretation, or approval promulgated by a government agency or instrumentality; or
(c) under this chapter for a violation if the merchant establishes, and at the time of the violation, is implementing, procedures reasonably calculated to prevent the violation. Subsection (b) of this section applies even if, after the act or omission has occurred, and the rule, regulation, interpretation or approval is amended, rescinded or determined by judicial or other authority to be invalid for any reason.