Final answer:
When a customer wants to dispute an ACH transaction or a debit card/ATM/bill pay transaction, they should contact their bank or financial institution and provide the necessary details for an investigation.
Step-by-step explanation:
When a customer wants to dispute an ACH transaction, the first step is to contact their bank or financial institution immediately. The customer should explain the situation and provide any relevant documentation to support their claim. The bank will then investigate the dispute and may temporarily freeze the transaction while conducting the investigation.
For debit card, ATM, or bill pay transactions, the process is similar. The customer should contact their bank or financial institution as soon as possible and provide all the necessary details about the transaction. The bank will then initiate an investigation and work towards resolving the dispute.