2008 Land Rover Discovery 3

While driving my land rover a horrible noise occured from the engine, I stopped and It was picked up by land rover assistance. The dealer contacted me to let me know there was no oil in the engine and I need to pay £8000 for a new engine. There are no leaks and the engine sounded and drove perfect until then. There was no warning light or any indication it was low on oil. When land rover spoke to me I mentioned there was no warning light and I was told the oil was lower than the sensor. It is still under waranty but because it 5000 miles over service date I need to pay? It had done 45k and had its first full service at 20k. Up to now i've had suspension trouble and tracking trouble where the tyres wear because of the car leaning to one side.