Could be, have you had a look inside that switch (I assume you mean the one that stuck) to see if everything looks okay? - With the power off.Obviously it's a 9.5 KW. Well spotted, not sure why I thought it was 7.5.
Would the failed neutral be due to the main switch going ?
The fact that your shower is rated at 9.5kw (41.3 Amps) that is getting close to the current carrying capacity of 6mm2 T&E which is 46Amps when clipped direct you may have to raise the size of the T&E to 10mm2.
Also what is the size of your MCB and is it RCD protected?
Gave you one that Gainsborough recommend.What are my best options now for a 9.5 KW ?