are you serious? then i am going to protest every charge that comes out from now on as presented early. I think you are stretching the REG a lot to allow that kind of manipulation. Visa will not allow you a chargeback without proof.
There are two issues here. First is the one about this topic. This type of dispute has no Chargeback right. The consumer is not disputing the validity of the transaction, just the earlier date it posted. The Issuer has the ability to adjust the transaction without involving the merchant since the merchant is due payment anyway. This could qualify as a Compliance right but why bother?
The second is the issue you raise regarding proof and, to answer your question, I am quite serious. You have every right to dispute any and every transaction on your debit card account. That is a liability the bank takes on in issuing a debit card and too many banks don't recognize this. However, depending on what you assert depends on how much work the bank has to do to either prove or disprove your assertion. Chargeback rights are unrelated as CAWorkingGirl points out - that is a possible course of action for the bank but not the only one in performing a reasonable investigation.
On point, nowhere in Regulation E (or Z for that matter) will you find any requirement that the consumer has to provide proof to
assert a claim. You cannot deny a claim because the consumer lacks proof, period. There is no other interpretation because there is no requirement in the regulation for any proof. This applies to any Billing Error, not just the type being discussed here.
After a reasonable investigation has been done, you may request proof
if it relates to the investigation. For example, if the merchant disputes the validity of the claim, you could ask for proof to show the true transaction date, heck you could even ask for a signed document with the true date. However, you could not deny the claim if a document with the true date lacks a signature because the evidence of a signature has nothing to do with the asserted Billing Error.
What constitutes a "reasonable investigation" is another matter entirely and changes from Billing Error to Billing Error. Also remember that far fewer dispute types qualify for a Reg E Billing Error status than do for Reg Z Billing Error status.
On your Chargeback issue, Visa and MasterCard require very little if anything nowadays in the way of documentary evidence for any of their Chargeback rights. They do require their applicable dispute forms, but rarely do they require proof to
initiate a 1st Chargeback.