Had my Economy 7 fixed a month back as no hot water. Since then water far too hot and immersion heater and cold water makings lots of noise, sometimes like something being released. On Friday it was so bad that steam can out the toilet and cold water tank boiling hot. Got a different engineer out. They said they couldn’t quite understand it but possibly due to me having booster on too much. Thermostat checked and turned down to 60. Kept off all weekend. Put on again last night to be awoken to same strange noise like something being released and boiling hot water. Anyone know of an expert in super 7 economy seven immersion heaters who knows what they are doing and can prove qualified? I have spent nearly 400 already and getting nowhere.