It would be far better if DL had a simple customer-facing statement such as, "the matter is under investigation. Because we take these matters seriously and all investigations are different, we do now know how long this one will take. We do our best to complete this in a thorough way."

Something like that does not disclose anything by way of a time-frame and also makes it clear to the customer that there won't be any more detailed information coming.

The alternative is to tell everyone that it may take as long as 90 days, knowing that it won't take that long.