Rob Waghorn
Hi Sonia. The problem is the diaphragm on the balvalve. It can also slow up how quick the cistern refills after flushing. It is possible to change the diaphragm washer but it maybe best and more cost effective to change the whole valve. Put the job on ratedpeople and I would expect you to pay no more than £65 to do the job. Hope the Helps. Robert.