No. You have to complete your investigation whether or not your customer gives you help. All he must provide is the information describing the transaction, his account and why he thinks it's an error.
Yes, you may ask for help. No, you cannot require it. I suggest you ask the utility company if your customer was liable for either of the utility bills paid. If not, you've pretty much got the documentation you need to approve the claim.
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John S. Burnett
BankersOnline.com
Fighting for Compliance since 1976
Bankers' Threads User #8