Reference: [account number]
I write further to my telephone call on [dd/mm/yy].
On [dd/mm/yy] I received an email purporting to be from [bank name] and responded to the request for bank details contained in that email.
I had no reason to suspect that the email request was not from [bank name].
[Give details of the transaction]
I would be grateful if you would credit the sum in dispute back to me and provide your confirmation that this has been done.
I look forward to hearing on you by return.