Not fullfilling their warranty obligations

I bought a Gwm 2.5Tci.. Steed 5... 2014 double cab diesel bakkie. Engin was replaced at 72000km due to over-fuelling.. New warrenties were given. Then the same problem occurred again.. over-fuelling. Oil was pushing out the dipstick.. etc. Mileage is on 114 000km.. only done 42000km now with the new engine.. less than the previous time. GWM SA refuse to honour the warranties because i have gone over 100 000km on the odometer. They say once i am over 100 000km.. all warranties expire. I believe they are still liable to fix the bakkie because i have a new engine.. and new warranties are given. Can anyone advise me.. who can help. I need to take this further. They offered discount on their spares / parts... but it is still too much.