Smug, rude and completely out of order

My partner has just had his ex make a claim against him as suggested by him. Two days later gets a call from the CSA about a women he had a one night stand with 5 years ago says he is the father and needs a DNA test to confirm. His name is not on the birth certificate.

The smug investigating officer said he hoped that my partner was ready for a hefty back payment IF he is the child’s father. He also said that he was a very hard man to find and that the case had been sat on his desk for 4 years. You can find my partner on linkedin, Facebook, his company that he was working at the time where he was doing work at her house and she had his mobile number.

Where does he stand with the back payment? The CSA have been so rude and completely out of order in this case.