TFoxe

Hi to all. My other half has 2008 A3 1.9 TDI which starts easy in the mornings but after it warms up and is then stopped it will turn over for about 15 seconds before starting as opposed to the 2-3 seconds it used to take, and still does first thing in the morning. Any ideas? It has had a new fuel filter and is serviced regularly. It also has 160k miles. Thanks