I have just had a new kitchen installed. My shower is now acting differently. The temperature is going very hot and then very cold. also when the shower is adjusted to a cooler temperature the low flow light comes on.the pipework under the kitchen sink has been altered.The mains feed used to leave at right angles now it rises verically and then returns to floor level prior to leaving at right angles.Is this part of the problem? the pipework is 22 mm.