I drove 60 miles, yes 60 miles and my caravan unhitched! I drove over a range of surfaces including speed bumps at speeds up to 55mph (not over the speed bumps!) and at about 10mph while accelerating from standstill at traffic lights the van unhitched. I had checked the hitch 3 miles from setting off and everything was fine, there is no doubt in my mind that it wasn't hitched up correctly, if wasn't the van would have come off at the first speed bump or any of the bumps ridges potholes that are called roads.
Alko sent out a technician who examinded the towball and hitch, there were no scrapes, gouges marks on the towball or pads, he said he had no idea why it unhitched and stated that the ball and pads were fine, so it must be user error.
A temporary 2004 was supplied while alko investigated my 2004.
Alko replied by sending me photo's of a ball which had deep gouges in it which mean't that it had been incorrectly hitched. What a load of rubbish! Now I am not the sort to accept down right lies and false evidence especially as i took my own photo's of the ball (sneaky heh!) I have been in contact with the editor of a caravan magazine (not pc, they ignored me when I wrote to the ed) who has been investigating this area and some very interesting things were said. It seems that some couplings may develop hairline cracks (found through xray analysis) which could allow the van to become unhitched. I do not have a 2004 anymore but the latest 3004 which has a much higher weight limit, supplied free of charge and fitment at my home address! I was not given my 2004 or ball back. Why is it that that the 3004 has a weight limit of 3 tons when the 2004 is 2 tons and caravans weight much less that that even when loaded. I leave you to make your own mind up about this, but take a good look at your 2004.
Everyone always assumes user error, this should not be the case. PC magazine will not be interested in exposing this as it might hurt advertising revenues. Alko and other manufacturers will always say user error, it is not in their interest to say otherwise.