Slow service delivery on resolving car VIN number that I'm sharing

Thank you for accepting. I have a problem. I bought my car in 2010 at a Ford dealership in Cape Town, after some time Ford recalled all the car models to fix a manufacture problem and when I took my car in I was told that it has already been done, I was a bit confused then I went home and left the matter, July this year the cars were called again for something else and when I took mine in I was told that it was do e in Springs and I stay in Cape Town and never been to springs. I then started asking questions and only to find out that I am sharing a VIN number with a lady who stays at springs. I emailed Ford several times and all I get is 'we will get back to you after investing the matter' it's been over a month and I'm still waiting for resolution. I'm afraid that should anything happen to my car I will have no leg to stand on as they will tell me that I don't have a car because my VIN belongs to someone else and not me.