Hi, we have a combi boiler and our shower runs off it. Last winter I noticed the temp in the shower would fluctuate. I would keep turning it up for hotter water and the temp would rise but then drop again. Once it had dropped, if I turned the temp down it would actually go hotter! When the weather got warmer it stopped doing it, however it’s now started doing it again. No issues with the radiators or hot water taps. Any idea what the problem could be? Cadent changed the gas pipes last year, would that have any effect? Many thanks