Hello again Ewan.
The comment I made about raising the entire van on two levelling planks to create a more pronounced slope from the back to the front of the awning had two purposes. Firstly it was intended as a helpful suggestion to you and secondly, I thought that it might prompt the more experienced members of the Forum to provide their expert opinion.
I say this because we have exactly the same problem as you. Our lightweight awning turns into a paddling pool every time there is moderate to heavy rain - complete with the blocked door and buckled frame. Thus, the 'two plank' suggestion was a method I was considering as a cure.
However, since that suggestion was made, I have had cause to speak to the dealer about another issue and as soon as I mentioned the awning to him in the hope he might come up with an answer, his immediate response was; "Send it back and we will give you a full refund".
So from this unquestioning reaction, I suspect that the problem might be more widespread than is realised and that further more, there is no easy solution. The thing is, the awning takes up so little storage space and is so easy to put up that we are loath not to hang on to it. Let's hope that someone comes up with a flash of inspiration
Olivier.