Online Lawnmower purchase return

I bought a 160cc wolf lawnmower online revived in July, wheel falls off on second time being used. I called the Delivery manager at the Woodmead branch and he said they would pick up the lawnmower, it was a week so I took into the branch, they arrive at my home at the same time. I am then told it will take 4 to 6 weeks to fix the lawnmower. Its unacceptable for them to take this long to fix the issue. My Gardern will become a forest the 4 weeks. Customer service at makro is gone poor.