Sent Brush cutter in for Broken fuel line

I have used my brush cutter 43cc for a total of 5 full tanks, I then found a problem where by it starts but can't get to speed and then discovered a slit in the fuel line. So when I sent it in for the repair, with no questions asked, I received a quote for R1100 to fix a 6 month old brush cutter that I only use on my property. I then inquired about all the extra line items and said that I used the wrong fuel. I really don't believe that because when I handed that brush cutter in the engine was running 100% it was only the fuel line that was leaking. Now, does the engine stall because I press the throttle and there is no fuel going in or is it the wrong fuel mixture? Wrong fuel mixture you may say, then why can it idle then? I have handed my machine in December 2014, please can I get it back in working condition.