hot water temperature problem

[bovril360]

hi could anyone help, ive got a ferrolli modena 102 and i cant control the temperature of the hot water. its coming out to hot to touch. the dial on the front turns but it doesnt alter the temperature. anyone got any ideas on whats wrong with it and how i can fix it. thanks

 

[Billy Bob Bob]

could be a ntc or over gasing or a blockage in the main heat exchanger you need a gsr engineer