Classified Adverts

Why can't people who have advertised their caravan for sale on the classified section and then sold it "not remove it from the site".  I am looking to buy a new caravan and have contacted at least four people only to be told that it has been sold already or not even replied to my text or phone message. I sold my van and Deleted User it the next day,  It is so frustrating when you think you may have found the ideal van only to be told it is sold and some of these adverts were posted up to 2 months before.