Hello Posy
It has happened to me too!
Unplug the machine and pull it away from the wall so you have access to the drain hose.
Protect the floor with newspaper.
Lift the hose from the standpipe and put the end of the hose into a large bucket.
The water will start to drain out of the machine.
When the bucket is full,raise the hose and the water will cease to flow.
When no more water comes out,put the hose back into the standpipe.
Turn the programme to 'off' so that the door latch will operate.
It's easy when you know how!
Good luck. Go and get that bucket!