You might have chargeback rights if done on a debit card but that is a non-Reg. E matter. The only Reg. E dispute she could have is if the merchant promised her a credit, verbally or in writing, but did not process it. That would qualify as a Reg. E dispute for non-evidence of a credit transaction.
That doesn't mean the consumer gets to keep the provisional credit you might give while investigating; but if properly asserted, you must do a reasonable investigation. You cannot just dismiss a credit claim just because what she previously asserted was not a Reg. E dispute.
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My opinions do not necessarily reflect those of all the voices in my head.