Appalling service

I don't even know where to begin to express my dissatisfaction with our recent sale at Kia.We bought a pre-owned VW Golf 7 GTD through a sales agent Michael Denke 3 weeks ago. On the day of the collection of the vehicle we had difficulty starting the car, he assured us that everything was okay.The very next day, I got stuck taking the kids to school with the car and it showed alot of error messages on the dashboard, we called Michael and he requested us to bring the vehicle in and my husband and  I took the vehicle back. He went and bought a battery and returned the vehicle to us. The very next day, it took about 20 seconds for the vehicle to start, we still called him regarding that and every time he told us he would speak to his manager and revert back to us which he never did, because we constantly had to call him and follow up. As i was driving sometime last week the car had a kick and the speed immediately reduced and there was an EPC error message on the dashboard. The rev count was not reading correctly and when i tried accelerating the car made a lot of noise.I immediately drove to VW and asked them to diagnose the vehicle for me, upon checking they picked up that the battery that was fitted on the car is not an original battery for this specific VW hence the issues and this also affected the start and stop function. We immediately called Michael, this was last week Tuesday, till to date we have been calling and he is ducking and diving expectedly so, he made a sale and guess what the car is no longer his problem. I honestly regret buying a VW vehicle from Kia, it was my first ever experience with Kia and thought it was a reputable dealership but the experience has left a bitter taste in my mouth. I haven't celebrated nor told people about buying a car, because the question is which one? The parked one, the problematic one! If my issues are not sorted out by today, unfortunately i'll be left with no choice but to return the car and call Standard bank to cancel the deal. I'll go look for a vehicle elewhere.