Hi everyone advice needed please. Got a boiler fitted in October last year and a couple of days ago got a error 75. I called the plumber who fitted it and he said to contact valiant so I did and they came out.the valliant engineer said the fault was because there was crap in the system and showed my wife the dirty water. There is a sentinel filter fitted. He then said that he would only be able to fix this error twice under the warranty. And left. later on there call centre called and said the system needs power flushed and they could do it for £456. I called the fitter of the boiler on two occasions to ask his advice and he said he would call and he failed to turn up what do I do now guys need some advice please. Thanks jay.