Traffic Offences for a car that was trade in

I traded in my car Dec 2014, I believe my old car was sold few weeks after trade in. On the 6th of March 2016 my drivers licence expired & had to renew it, after long ques at the traffic department I learned that my previous car has traffic fines with warrant of arrest post trade in, in January 2015 to be precise and for that reason I cannot renew my licence until the fines are settled. I went to speak to dealer principal who promised to email me a letter confirming the history mentioned above. The next morning which is today 30/03/2016 I called him just to remind him about the letter & he promised to email during the course of the morning. After 13h00 when I realised that the email hasn't came thru I went to see him and he had one excuse to the other about not emailing the letter. Eventually he wrote a letter which was rejected by the traffic station as they told me to either pay the fine or transfer the fine to the new owner which I obviously do no know. I had to drive back to Imperial Select on Bram Fischer for the 3rd time Martin told me to drive at my own risk until he finds a solution & said \I cannot talk to SOMETHING like you who doesn't have manners get out of my office\" "