I have an Ideal Mini C 28 boiler, about 8yrs old. It has started cutting in and out and not supplying a constant flow of hot water. You know the problem, you're having a shower and all of a sudden the water goes to extremely cold and shortly afterwards the opposite, almost to scalding point. I am not a plumber but am just looking for some advice as to what the problem might be and how to rectify it. I have tried shouting loudly at it , but that didn't work. Any help/advice gratefully received.