Terrible service

The terrible service I'm getting from Hyundai cannot be matched with anything I'm so frustrated and regret buying a car there. I bought a car in December 2023 and I realised that the gearbox is faulty and they took it for a month to fix it, I was never compensated for the loss. Now I'm struggling to get paperwork that shows the cars service history and warranty plan , it's been 3 months now asking these from the sales guy but he's now ignoring me and when I call his manager they both ignoring me. I'm so frustrated and I feel like I've been taken for granted. I bought the car thinking it has a service and warranty plan but to my surprise it doesn't. What am I going to do with a car which doesn't have a service plan?? I really need assistance before I take this to the ombudsman. Hyundai doesn't respect it's customers and the service is really poor.