As noted, the item BLR describes is not a product of Check 21. It's an ARC, a check converted to an electronic entry under current NACHA rules.
They really p*** consumers off, but the current remedies are as John notes - the consumer has no choice other than changing vendors. If a bank is receiving complaints, the brochure cwilliams links is an excellent response. However, start your explanation to the consumer with the concept that her complaint is with the merchant, you cannot "fix" the problem.
NACHA has published a request for comment
on a proposed rule that would give consumers an opportunity to "opt out" of ARC conversions. NACHA claims they thought merchants would voluntarily offer an opt out.