Defaming email

I’m beyond annoyed with the uncanny service and words that were used by your institution. Firstly how dare they send me an email asking me to explain why I got a payment inciting that they are proceeds of *****? It was during the holiday season and obviously any normal human being will receive money at that time. Your email was beyond defaming and disrespectful. If this is not rectified and I do not receive and email of apology or explanation I have all grounds to sue for defamation of character. How can I ask someone who is a family friend to provide were they are getting their money when they have decided to extend a giving hand out. I’m beyond annoyed. I would like this dealt with urgency