Hi, I have just picked up our new 540 Conqueror and have noticed that all of the grey plastic surrounds to the locker doors have white patchy stains on them.Swindon Caravans have tried to remove these marks without success, and it would appear that swift are not being very helpful. They have now contacted Thetford to see if they can help, Has anybody come across this before or know of a product that can clean this off as I currently have a one day old caravan that looks as if it is 2 years old any suggestions please.