Warranty wasted

I am extremely dissatisfied with my Samsung microwave and the after-sales service I've received. Within a year of purchase, the microwave stopped working. I was advised to take it to the Samsung-authorized repair center in Pietermaritzburg, where they replaced a fuse. However, the microwave continued to work intermittently. Despite taking it back multiple times, the repair center only kept replacing the fuse without identifying or fixing the actual root cause of the problem. Now, the appliance is out of warranty — and I'm left with a faulty microwave and no real solution. I feel let down by both the product and the service, and I don’t know what to do next.