Dissatisfied First Time Owner

I regret purchasing my first car through hyundai woodmead as i'm not happy with the way things are as we speak. I purchased my car early this year around March and issues with the contract signing as they had load shedding stories...initially after many back and forth i and confusion i got my car. Fast forward to last week i called for a service booking and explained everything to the lady on the phone that i am a first time buyer and don't know how it works as i was told by the sales guy Zane Dunaj to call when i am ready and they will advise, of which that's what i did. All went well on the phone with the lady i spoke until the actual day of the booked car service, i got there only to be told that i have went overboard with my mileage and i explained to them that nobody gave me an actual set number for mileage of when to come then we disputed the matter for 30 minutes or so until they checked my maintenance service plan that i had with them only to find out that my service plan only starts covering from 75 000 kilos, then they called their partnering maintenance company to amend the contract for it to start at 60 000 kilos as it had expired in January 2019 before reaching the specified mileage. I then was handed the telephone to speak to the lady who advised me that there is nothing they can do to amend the contract as it was never updated by the sales person that was selling the car to me at that time (Zane Dunaj) who no longer works there now. I told the services booking consultant what the other consulted said on the other side, he then asked for another contact from that company who then advised that i said my contract to them so that they can see how can assist with amending the it, i was told that they would contact me to let me know the way forward an i am still waiting. What frustrates me is that the person who assisted me form day one was not honest and now that he is not here to answer for himself i get to be blamed as the customer with no assistance and being sent from pillar to post....I am paying for the for a mistake that is on their side for not updating things and not hiring professional staff at my expense as a customer, i am not enjoying my purchase now with all that i have encounted and have no solution nor support from the dealership as a paying customer.They have received their money and don't give a damn about aftermath of their customers, I am so angry at the rate of customer service i have received thus far and lack of confidence that i have been instilled. I have like i am being taken advantage of as a lady and is paying for someone else mistakes as one of the colleauge had stated to me on that day that the sales person who assisted me with my purchase was called nyaope boy (which means druggie) an dthat he was crazy, with that being said and aware of i still get the backlash of all his mistakes as its clear he was never professional and knew the type of character they where dealing with, so why don't they own up to their mistakes as a dealership and resolve this matter without me being punished as a paying customer and left to figure out things myself.