Applying Transaction to Customer causing Affiliate email

OC V3.0.2.0
Test ordered a product as a customer (not guest) for $100
Received the email notification
Used payment 'bank transfer'
Assuming the customer transfered the money into the account but not all of it, I applied a Credit the following way.
Customers - Customers - Edit - Transactions Tab
Lets say I received $50, so I applied partial payment of $50 and changed the order status to "partial payment received"
Why do I receive as the customer an email with Subject: <storename> - Affiliate Credit
That is confusing, nothing to do with Affiliate, am I wrong here?
the Body of the email: (the last sentence could be reworded)
You have received CHF50.00 credit!
Your total amount of credit is now CHF50.00.
Your account credit can deducted from your next purchase.

In admin/language/en-gb/mail/transaction.php file, you can replace the: - Affiliate Email with: - Customer Email .