Well LDT in the early stages of playing the concertina you went out and bought a melodeon and now you have a fiddle. Way back then I said you were a little butterfly flitting from one instrument to another. Most here will tell you that to play any instrument well you have to dedicate a lot of time and effort practising and it all starts to get better. You like the melodeon because for one button on the left hand you get a chord, this enables you to concentrate on the right hand, but the notes for those chords are there on the concertina and with a bit of hard work and timing practice you will play them. You purchased a very nice concertina ,what a shame to waste your money by not playing it. I am not nagging you (I hope). For the time being keep going on the melodeon as you can enjoy yourself more with it and that is the main criteria. Perhaps we can sit down at a future festival and I can help you with the concertina and make you settle for a while.
Al