Mercedes Bens not taking responsibility for substandard material used

i have a 2019 C180 AMG line which is still under a moto plan , now the passenger seat has developed a tear which i deem pre mature wear as the car has just over 2 years. i contacted Mercedes Benz South Africa and i was advised to take it to the nearest branch and i took it to Mercedes Benz Grand Central, they took pictures and sent for authorization and now i am told that Mercedes Benz can only pay 75% as a goodwill and i am liable for R25%. i find this very strange because the car has only in existence for just over 2 years and other cars that i own have been in existing for over 8 years and their seats are as good as new. i am so disappointed in Mercedes Benz i would expect this kind of services from small brands and i need to take this further i cannot pay for damages that occurred due to substandard materials used. i hardly passengers have passengers in my car and this should not be happening too soon.