When flushed, my toilet just keeps refilling with water. The "thing" that is supposed to come up and float, doesn't stop the water refilling.

How do I fix this please?

Martine, London, April 2009

The floating thing that you are talking about is called a ball valve - as it rises it compresses a rubber washer against the water inlet, so stopping the flow. The washer has failed, so you can either replace just the washer - several different types though - or have a complete new fill valve fitted.

John, April 2009