Service Plan

I booked my car at Bloemfontein Linsaker VW for 120 000 km service and it was on 118 567 km. I hand it over car on 12/12/2017, they send the quote to motorvaps. The provider said its too early for me to service my car, since my last service was on June 2017 and claim that I should service only once a year yet their contract stipulates that I can service once a year or after every 15000 km whichever comes first. I called them same day and today but still they are not willing to pay that quote of around _R4700 , they said I should pay for myself. How can I pay for myself that money, yet I'm paying them for that service plan. Please help .