We have recently had our house refurbished and it seems to have caused a problem with the water pressure. In the kitchen, the hot water tap blasts out at first then drops to a drip and the boiler then stops heating it. You have to repeat this process 2 or 3 times before the pressure remains constant. The upstairs shower (mixer taps with shower attachment) used to be quite powerful enough but now it feels like you are stood under a watering can, and it seems to change from hot to cold the whole time. I think we have a combi boiler (I live in rented accommodation). Can anyone suggest what the problem might be or we can fix it? Thanks