Is there a drain plug on a renault scenic petrol tank?

My friend is a trader and I do various repairs on his cars. This time round he has made a beauty of a mistake. He has put 50l of diesel (cans) in his petrol car (oops!!) He did drive it about 200 meters and it conked out. Can I simply drain the tank and change filter? If so what is the quickest way to drain it? Bearing in mind I don't really want to drop the tank.
Many thanks Simon

simonsp
November 2011