Well, I think I owe you a closure on this saga. After countless test shots and a visit to a friendly repairer I am glad to announce that there is no problem with the camera. It appears that the problem is entirely with the person behind the viewfinder.
Firstly, I was told to test all the auto focusing points as there was suspicion that one or a few of them are at fault. Apparently these are the most common culprits when it comes to overexposure. After doing the tests (just 10 shots with all and then each individual AF point selected of an evenly lit subject) it appeared that the leftmost (in horizontal position) AF point had some slight tendency to overexpose but not to the degree shown in my test shots published here and on flickr. I was given an option to either send the camera for further tests to Canon Australia, which I was told, is a very long process and also will be at my own cost should they find that there is nothing wrong with the camera, or try to use it a bit more to see if the problem persists. So far I must say that no photo came overexposed. It looks like it was me (
) who caused the problem. How, to this day I do not understand, but I must take full responsibility for being clumsy and for making overexposed shots. In a way I am glad that's me, because that, I can fix. If it was the camera it would be out of my hands and I would feel rather helpless.
Anyway, I just thought I am going to tell you what happened and thank you again for looking at my pix and helping to resolve the problem