Service plan forfeit

I bought a vehicle when GWM had a special running last year 28/8/2014. At the time I declined the extension of the service plan. There was a delay in receiving the vehicle due to the wrong colour being delivered to the dealership. When having the vehicle serviced at 15000km, I was told my service plan had been forfeited due to the week delay in waiting for the correct colour. I was given an invoice and informed I had to pay it. I contacted the salesman, sales manager and director of the dealership asking to investigate the matter and requested a meeting with all 3. To date I have had no answer from them. I contacted GWM SA and was told they have no authority over the dealerships as they are all franchises. I am now at 30000km and need to have my vehicle serviced again. I have had no joy from both GWM SA nor GWM JHB South.