Thomann CMS-600 S C- Melody Sax

I bought one of these to play in a band with guitar/keyboard. Have always been an alto player but secretly wanted to try tenor. This seemed like a halfway house.
The sax has a nice tone and intonation.
It has a very awkward octave key on the right side of the button. It requires to you to rock your thumb forward and hold in an uncomfortable position.
I quickly got cramp playing this. This has never been a problem with the 4 other saxes I've played. I have managed to improve it by altering the thumb pad angle with sugru.
They also sent it with a clarinet mouthpiece and no reeds. They wanted me to email them pics of the wrong mouthpiece as proof before they'd send the right one which felt impolite and suspicious when they should have been apologising profusely for their cock-up. The eventually supplied C-mouthpiece doesn't have C-specific reeds. Tenor ones fit width-wise, but they are too long proximal and need to be trimmed. This was not explained.
Zinner who made the mouthpiece have gone tits-up which may ecpain the reluctance to send me one I would check if you plan to buy this sax that they have a supplier of decent C-melody mouthpieces.