poor quality machinery

I recently purchased a ryobi 52cc brush cutter at makro and within a month of usage the machine stopped and refused to start. I sent the machine in to makro for assessment ,who in turn sent it to Ryobi. I got a call 2 weeks later from an assitant at Makro telling me that Ryobi wants to charge me over R1000 to fix my brush cutter, stating i used the wrong fuel mixture, and burnt out the gasket , spark plug , pistons ect.... after trying to explain to the the makro assistant that I followed the Ryobi manual for the fuel mixture and the machine did not burn out or smoke( I have experience with using these machines and that is how I am able to establish the faults) it just cut off which probably was the air filter that was clogged and I didnt want to open the machine and check because of the guarantee . . . RYOBI JUST WANTS TO MAKE MONEY OF THE CUSTOMERS AND DOES NOT WANT TO HONOUR THEIR GUARANTEE . . . I called makro about 6 times trying to get some sort of understanding as to why I must pay for something that Is still under Guarantee!!!! furthermore I followed all usage instructions that are indicated in the user manual.. so why should I be liable for this cost? All I got was transfered from place to place with nobody even having the decency to take my calls, and eventually when I did manage to get a hold of someone from the relevant department she was not able to provide me with any feedback regarding this issue .... I am very disappointed with the service from makro and the RYOBI product that I purchased . . .