OMG, I have spent seven phone calls and many, many hours regarding the same issue.  The payments department of merchant services says it is the customer's bank rejecting the payments.  Not true!!  We have checked.  It has happened to numerous customers all since mid February.  QuickBooks engineers, please get this issue resolved.  Also, I was charged a "reject" fee two times and they will not reimburse even though the error is on the QuickBooks side.