Did you know you can report these yourself? If you suspect a car has been parked illegally – on yellow lines, or outside the permitted times etc you can report them here:
www.oxfordshire.gov.uk/…/parking/illegal-parking
You can do this from a smart phone too, you need the make, model and registration of the vehicle and preferably also a photo plus the time and date of the parking.
The more reports there are for a specific area and time of day, the more likely that area will have an extra visit at that time.