I have recently had a new downstairs loo fitted (to replace existing one) It is a push button flush with 2 settings. When the cistern has filled the shut off valve closes with a bang that sounds through all the cold water pipes up to the shower room upstairs. can it be adjusted so as not to be so harsh. (As you look into the cistern the water inlet is to the right with a small ball cock on a small lever. the flush button operates using a wire system)