Thanks Jokeyman123 and G0tchas!! I finally managed to resolve the issue about a month ago (apologies for the delay informing). I mentioned I had contacted with a few users of the Casio music forum and that seems made them look into the case again. They recognized I was right and then tried to cover their mistake with an excuse about hard factory resets. Bullshit, they realised they were wrong and had to send a new unit. So, even though the journey has been a bit painful, we can finally enjoy this piano at home as Casio designed it. I agree it is an excellent unit. Of course there are better models, but value for money I reckon it is a very very good one. More than enough for our level. Thanks again for your help, I could not have done it without it.