Just sitting here and thinking about Colins' problem.
First is the van is a 2011 unit and as far as we know this issue has not been reported previously, so must assume it was working OK.
So, what has changed this year to bring the problem up? the weather !!!
This year has seen much more very severe weather with very strong winds, storm after storm, so to have this blowing out may be just because of that and there is very little to do about it , maybe spend some money on what may well turn out to be useless , or just find more sheltered places to park.