96. The merchant receiving the writing provided for in section 95 from a consumer shall, within sixty days from the date of mailing of that writing, advise the consumer, in writing,(a) that the billing error has been corrected, together with any credit charges erroneously billed; or
(b) that he refuses to correct the statement of account, explaining to the consumer his grounds for not acceding to his request to make the correction; in this case, the merchant must, without charge, provide the consumer, on demand, with documentary proof of his grounds for refusal.