Karcher high pressure cleaner problems

I have had my cleaner for about 6 or so years. When someone borrowed it they did damage to it, however it was repaired by Karcher. Since then, which was about 4 years ago, only I have used the machine, and exactly like I was told by the Karcher gent. I have only used it to wash the car, so nothing hectic. After having washed the car the second to last time, I then went to use it again, and it would not switch on. I took it to Karcher and when I got it back, I was told the nozzle was the problem, which I find weird as the machine would not switch on. I then washed my car with it and it worked fine. A month ago when I went to use it, it would not switch on, just like the previous occasion. When I took it in to Karcher, I was told there was bad news as it would not turn on. I have literally used this machine about 5 times in the entire time I have had it and now it is not working again. Karcher is also far from being the cheapest high-pressure cleaner, but what is the point in buying it when there are these problems with it, I may as well have bought a cheaper one. So frustrating.........