Wind this is awful, & really difficult to deal with when you're in the middle of it, you really need to keep phoning the police & reporting it, take photos, keep any notes, videos etc.
We live across the road from 3 schools, & a community centre, so over the years we've had problems with people parking their cars on the pavement, (all 4 wheels) meaning pedestrians were forced into the road because the pavement was full of car! School drop off & kicking out time is the stuff of nightmares! Several of the neighbours took to taking photos & emailing them to the local community officer, which led to them being in the street regularly & issuing parking tickets.
Try your local police force website & see if you can discover who is your local community officer, (we used to email pictures to ours) every time they park over your drive, call 101, get them to contact the car owner & ask them to remove it, the Police can technically have it removed, or ticket it for obstruction.
You need to keep contacting them, hopefully if it's your neighbourhood team, he/she will be able to build a case of anti social behaviour etc. & will work with you and the neighbours to get something sorted
Hubby has also suggested maybe you might need to go out in the middle of the night a few times, go bang on the door till they wake up, or dial 101 & get them to ring them & wake them up!
Check your local councils parking section, our LA have wardens out & about on mopeds, so they can zip around, they will ticket people who park over dropped curbs etc. I rang them on Monday, because we couldn't get the car off the drive, about half an hour later they were slapping a ticket!
Wishing you luck with it all, because you shouldn't be feeling bullied & intimidated in your own home, that's really not on