I would like to rub out

yesterday and start it again. I had tricycle trouble again.
I have not been happy with the new vehicle. Although there are issues with the old one and it is prone to need repair (hence the new one) I have still been using it while I tried to get used to the new one.
It is a different brand. I did not expect the ride to be exactly the same but I thought it was me. I would take it for a ride around the block and that would be about as far as I could pedal it.
Yesterday the Senior Cat said, "For goodness' sake take it a bit further than that. You have to get used to it."
I had to deliver something to someone who lives a bit over a kilometre away. I have no problems pedalling that far and even further, much further but...not on the new vehicle. I managed to get there and found I was not looking forward to the pedal back. There was also an ominous "crunch" and I suspect a bearing has already gone . (No, I do not weigh that much!) When I did eventually get back I had a headache and an ache in my lower back. I am still having problems today.
Yes, before you ask if I am sure it was the exercise on the new vehicle, it is the new machine.
The Senior Cat and I had another look at it. We knew the configuration was different but we had set the seat at the same height. It cannot go any higher or I cannot get on and off. As it is it I can only just manage it on this one because the cross bar is much higher than it is on the old one.
The two machines are almost exactly the same length and the handlebars are almost exactly the same height. What is wrong with it?
The configuration is actually quite different. The seat is at a different angle - and the crank shaft is about ten centimetres shorter. In short, it is simply badly designed. Even if we raised the seat by ten centimetres to try and accommodate the short crank shaft it would not be comfortable because the seat would still be at the wrong angle.
Our problem now is what to do with it. I have sent the bike shop an e-mail. I suspect I will not get a reply. Even if we send it back to the manufacturer they will simply want to "repair it".  They will say other people ride these without problems. (I suspect that such an answer would be far from true but it is what they will say.) We cannot, in all honesty, offer it up for sale to some other unsuspecting human. I cannot ride it, indeed should not ride it.
And, worst of all, I feel bad for the Senior Cat. He was the one who arranged all this. He thought he was doing something very special for me. I love him dearly and this makes me angry and disappointed for him.