Peter

Is yours one of the new Chinese Hohners? Mine's 30 years old and still in good tune.

Though it may sound a bit harsh, my suggestion about the "fingers disappearing into the holes" problem is to learn to play the instrument properly. Too many people play the melodeon with their hands like claws. One of the reasons why the buttons are staggered is so that you can hold your fingers at an angle and play the instrument so that your finger ends just go down to the level.

I sympathise if your instrument is out of tune but as for the conformation of the melodeon, it was ever thus with the Hohner pokerwork (and many other melodeons too) and it's best not to let it be the case of a bad workman blaming his tools.