OP, it occurs to me that since you are not the initial purchaser of the MBP in the first place -- you've mentioned that your mother was -- and since a look at your profile suggests that at this point in time you are also still what in the US is called "a minor child," meaning not of legal age (in the US, don't know about Switzerland) that this is one reason that people at the store don't seem to be respecting your thoughts, concerns and requests. Isn't it likely that some of those people might be more willing to pay attention and listen to your concerns if it were your mother, with receipt in hand, stating the issues and requesting a replacement machine?