Customers will be overjoyed when they receive a refund for an incorrectly completed payment because it’s much better if you spotted the error before they did!
An example letter informing them of the refund’s progress is provided below.
Sample 1: Letter confirming the refund of a duplicate payment
Dear [customer’s name]
[We / Our finance team] received a [cheque / bank transfer etc] from you on [date] for payment [on account no /for invoice no], however we noticed that you had in fact already made a payment for that [account / invoice] which we received on [date].
We have therefore issued a refund for this duplicate payment which you should receive within the next few days.