Boiler Pressure too High

[feilim]

I am having problems with boiler and radiators. The boiler pressure sat at zero for ages and the radiators would only come on if temperature was up full. This led to radiators too warm. The last time the gas engineer was out he tried to solve this and said to connect the filing loop back on and turn the gauge with pliers slightly. I done this and the pressure has went too high now. The heating still only works at a high temperature. Difference now is that the pressure is too high (at about 3) and I dont want it overflowing again and flooding my neighbour below. So basically how do I fix this to get my boiler working that I can choose the temperature of the radiators and the pressure comes down as well?

[The Builder]

The pressure valve should open at around 3 bar. Once it's done that, some water will escape, and the pressure will come down.
It sounds like more than one problem here. I'm surprised your man hasn't come up with something.
Things happening at the wrong temp. is usually down to thermostats, or more likely temp. sensing thermistors.
So many things to try. I would suggest getting someone a little more knowledgable possibly.

[shooty]

if you have a radiator bleed key, you can bleed of some water at anyone of the radiators to reduce the pressure. get pro advise on the other issues as the Builder said : )