Hello. My bank is trying to decrease the cost associated with mailing Debit CCDs to customers daily, which we have been doing for years. Our main concern is the time period in which we can contest a returned item (by a customer) with ACH. What is the official period for successfully contesting a charge with ACH, so that the bank doesn't end up paying the bill? We certainly wouldn't want to save in mailing costs at the expense of being billed for debits our customers contest, if we do decide to just send a monthly statement. What is the way to ensure ourselves against this?