Sorry to hear that. I thought the problem must be with the AF sensor --- but in your case looks concerned with lens ...
Could anyone explain why lens could lead to OOF? I guess some glasses were shifted so its focus range become too close?

Thanks for the message.
I guess it is not a common problem so probably the best thing I can do is exchanging for another camera.

I hope this is a problem only happen to a few cameras, ie it is not a design problem.
I received reply from canon but it does not help.

------------------------
Canon's reply:

Thank you for contacting Canon product support.  We value you as a Canon
customer and appreciate the opportunity to assist you.  I'm sorry to
hear that you are receiving images that are 3-5 cm closer/forward than
you had expected.

There is a possible remedy without sending your camera to a facility for
repair.  All you need is a pencil eraser and a clean dry towel.

    1. Check the camera by taking a picture without the lens attached.


    2. Remove the lens from the camera and use the eraser on the metal
lens                 contacts at the base of the lens.

    3. Wipe the area with a clean dry towel and attach the lens to the
camera.

If your camera is still having the same issue, you will need to service
your camera body and lens.