Maintenance Plan

I bought a car from SMG Cape Town in March, and the car is giving me problems. I booked it in at Sandton Mini and was told Maintenance Plan is not in my name. I have been liaising with SMG Cape Town since last week Tuesday and this has still not been resolved. Instead of assisting they are ignoring my calls. Mini Sandton cannot do anything on the car before this issue is resolved. I don't know what to do now because my calls and emails are being ignored.