My hot water isnt working, it runs hot for about 30 seconds and then goes freezing cold and after about 5 MINUTES it finally runs hot again, but only for about 30 seconds and then goes cold again! FINALLY got a plumber out this afternoon by some sheer miracle and he turned the tap on and it only bloody stayed hot FFS he tried a few things and even went on to ask if i knew the difference between all the hot water/central heating switches! Jeez (sigh) In the end he left and said it all seemed fine to him, have just tried running a bath for my kids and its bloody doing it again! FREEZING cold water, with VERY short bursts of hot how am i supposed to sort/fix this???? HELP!!!!!!! ANY help at all! Please