An incorrect amount is included in the definition of an error under Regulation E:
(1) Types of transfers or inquiries covered. The term “error†means:
(ii) An incorrect electronic fund transfer to or from the consumer's account
The challenge with this is that Regulation E is a very consumer friendly regulation. Therefore, I would work to get clarification from the customer so that you can proceed with your investigation. That said, if they aren't giving you anything to go on (i.e. not telling you what amount the charge should have been), I'm not sure how you could complete an investigation and you may have an out through the section you quoted in 1005.11(b)(1)(iii).
As Reg E disputes are often highly scrutinized by auditors and examiners, if you are unable to conduct the investigation due to a lack of information, make sure you clearly document your file so that the explanation is clear.
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Adam Witmer, CRCM
All statements are my opinion, not those of my employer, and should not be taken as legal advice.
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