Here is a sample template you can use to write an acknowledgment letter for a loan.
To [Recipient name]
Dear, [Recipient name]
This is to acknowledge that [Name] has received a loan of [Amount] from [Bank name] on [Date]. The reference number for this loan is [Number].
As of this date, the outstanding amount owed by [Name] is [Amount]. This loan ends on [Date] after which the lender must return the amount with [Number] percent of interest per month.
This letter has been provided to [Borrower name] upon his request negating any liability to the bank.
[Name of bank]