Another reason for going back to the manufacturer is they should have recorded if the recall has already been carried out on a van provided you can give its VIN number.
I would like to take this opportunity to advise that the recall would have been done automatically when the caravan was serviced by an Elddis dealership, but not if it was done by an AWS technician.
In addition, if the caravan owner never advised the Elddis dealership of a change of address then they would not have received the recall notice. Of course there is no obligation to notify anyone of change of address of a caravan owner.
However at an annual service, that is if the owner had the caravan serviced annually even an AWS technician should have advised about a recall even though they were not authorised to do the recall.