Taken for granted by Halfway Ford managers

Hi there, my car it is still with the dealer Halfway Ford County in Port shepstone since last year December. they denying to fix it as it is a return job and they trying to push the blame away. I hope top management from America can assist me as soon as possible if South Africa management can not, i have all the supporting documents proving that the dealer is reliable. They changed the services manager who was rude and aggressive towards me and now again the new service manager he is not willing to help as well.