Cold water in the morning

HI Mike

i got a problem with our boiler pulsacoil a class which is connected to an electricity 7 meter, which means its heat the water up at night , so that we have hot water in the morning and throughout the day. For some weird reason and nobody touch the thermostat, it no longer heat the water at night, it does it during the day now which means that every morning we have not hot water. Something else i noticed, it has become noisy in the morning when it is filling up the tank, you can hear water being filled into it.
I was wondering whether you could offer some advice