Hi, i have done this before but this time i have a problem. trying to isolate hot and cold tap in kitchen managed to turn screw on pipe for col d water hot is completly jammed and will not move despite large amounts of WD40. So i unscrewed for tap and was going to place a plastic push button cap on as I have before, I have done this before without having to cut the pipe, however this time the ut at top of copper pipe wont come of HELP-
