How to verify bank account that a DD was taken from in Receivables?

Hi,

A customer has 2 banks account and we mistakenly used the wrong one as instrument on an AR transaction. We reversed the receipt and changed the instrument. But the customer advised that the next DD was again taken from the wrong account. Yet, the corresponding receipt shows the correct instrument number. So we think that the customer might be mistaken, but aren't sure how to check. Can we be confident that the instrument number shown on the receipt is definitely the one from which the funds were taken? If not, where else could we find confirmation of which instrument was