After her friend cancelled the meeting, Ms Sloane was about to leave the park when a car full of people approached her asking for cigarettes.
The group consisted of at least three males and two females who all appeared to be under 18, she said.
"As I was going to hop into my car they've u-turned and pulled up behind me and three of them have actually hopped out of the vehicle and asked again and I said no," she told the Herald.
Ms Sloane said one of the females then grabbed her by the hair and dragged her from the car on to the ground.
"At that point I was hopping into my vehicle and they ran up from behind me and grabbed my hair to pull me down and brutally kicked me in the head several times."
During the attack, one of the other teenagers grabbed the keys out of her car and ran back to their vehicle. Ms Sloane could see her distinctive key ring in one of the women's hands.
"All that was going through my head was, 'You are not taking my belongings, you're not taking any of my personal things, you're not getting away with it'," Ms Sloane said.
She ran to the car as it was driving away and tried to stop the group.
"I was half in the car trying to get the keys out of their ignition and in that process they managed to smack into a big huge pine tree and that's where the vehicle stopped."
A witness then intervened, Ms Sloane said. But her ordeal was not yet over.
"One of the ladies from the left side of the car hopped out and ran to my car with my keys to try and start it and take off with it.
"So with the adrenalin rush and everything, I just opened my car door, I just grabbed her and pretty much hiffed her out of the car."
The offenders then fled in their own vehicle, which is believed to have been stolen.
"All I was thinking was to get them the hell away from me and my car," Ms Sloane said.
A spokeswoman for Counties Manukau Police confirmed they had spoken to the victim and were seeking three males and two females who left in an allegedly stolen vehicle.
Ms Sloane had posted about the incident on Facebook to increase awareness and the post had been shared widely. "I'm just saying to everyone, no matter where you go, no matter what time of the day it is, you've just got to be ready for anything to happen."