It sounds like the customer is trying to pick and choose which "unauthorized" charges she would like to be reimbursed for. It doesn't work this way. From the perspective of Reg E, you need to know when she first discovered an unauthorized electronic funds transfer. (The first charges were in March, but when did she see them.)
The customer would be liable for $50.00 of the charges that occur up to two business days after see learned of the theft of her card. She would then be liable for up to $500.00 for charges that occured between day 2 and day 60 from when she discovered the theft. If any charges occured more than 60 days after you delivered the March statement on which the first unauthorized charge appeared, she would have unlimited liability for those. Just because the customer did not tell you right away does not mean that she is autoatically liable for the full amount. You cannot set aside the liability schedule of Reg E 1005.6
For help with the math check out
AndyZ's Reg E Liability Calculator. You can't require that she file a police report, but if the bank sustains a loss, as the financial victim you have the right to file a report and seek reimbusrement from junior directly.
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