Seems like you have been treated badly barbara there is no excuse for not compleating the benchmark checklist , every gas appliance which needs registering with gas safe is entitled to a free gas safety check by a representative employed by gas safe all you need to do is tick the box in the paperwork that should have arrived with your gas safe certificate . as i have said before the water temperature coming out the ground this time of year is only around 10 degrees your boiler can only raise this by 35 degrees at a flow rate of 10ish litres a minute so if you turn your hot tap full on or your shower then the cold water passing through your boilers plate heat exchanger cannot be heated up enough to provide you with 55 degrees of hotwater the only way to get hotter water is to slow down the rate it passes through the boiler this is what your installer would have done at the stopcock or at the boiler , this is always a issue in winter with a combi boilers you could fit a flow restrictor (ECOSTAR PRODUCTS) to your shower head which will only allow 8 litres a minute of water to come through your shower head you will see the hotwater temperature will be better and you wont notice the slight drop in pressure as you can have a hotter shower , your baxi boiler has a 7 year manufacturers warranty and is a very good boiler and should give you years of service if you look after it and have it serviced every year . kind regards kop
