looking for reasons not to fullfil garantee

I bought a TRIMTECH 43cc heavy duty petrol **** eater in late December 2015. It had a two year warranty. It stopped working at the end of February 2016, approximately 60days after I purchased it. <br> I returned it to Makro, who in turn sent it to its supplier Lawn mover for Africa, to repair it. Now they came back saying that 1) the filter is dirty, 2) the plug is dead 3)the carburettor is dirty and 4) I didn't mix the 2stroke mixture correctly, which I know I meticulously did. They now want R463.65 to attend to a two month old machine, which was used only twice during the time that I have it. <br> <br> How would one dirty the filter, plug and carburettor deliberately. The machine was used to cut grass, which it is made for.<br> <br> Can one come up with anymore reasons not to fulfil one's warranties. This is pathetic service, and I will not buy equipment from MAKRO again.