electric shower getting too hot

Hi, Ive got an electric shower seems to be suddenly too hot, is it possible that this is caused by having the wrong head on it ?
it does say only use with original head but I think its been changed, can it make that much difference ?
thanks
ps its a gainsborough 9.5 se

 

Have you removed the head to see if the issue reoccurs?

 

have done that its still overheating dangerously, made a clicking noise first, steam came out , surely there should be some overheat protection ?
thanks

 

Should be some overheat protection, has anything else been altered as well as the head?

 

There will be a thermostat somewhere in the shower also an anti scald device.

 

There should be a thermal cutout if it overheats , sounds like something has gone very wrong

What shower is it?

 

New shower time ,not worth trying to repair.