The facts are that the MOT was stamped- no spring issue..
You had it inspected - no spring issue...
Surprisingly, the dealer doesnt think there was a spring issue..!
If you want to start pissing them all off..its a free country. Have fun...!
If you want to achieve more than puffing up your chest, & taking your principles for a short walk, I'd take a pragmatic and civil approach....
The "Maserati" tax is alive and well...save your strength !