Cracked sunroof on a swift caravan

We purchased a new Swift Corniche 3 months ago and 3 weeks ago the sunroof cracked. This was reported to the dealership straight away and we contacted them today as we have not been notified of a repair date and have been told that the earliest date could be  end of September as they are not in stock.

Our son covered the crack with some strong tape as we were going away in the caravan. My wife woke at 2 in the morning to find her feet and bedding were soaking and we spent all night mopping up water. We contacted the dealership to report the leaks and they said they had reported it to swift and there was nothing they could do. Swift suggested we get a mobile repair service but none were available. Luckily the warden on site managed to do a temporary repair because now the seal had cracked and was leaking as well. We don’t how long this temporary repair will last and the dealership don’t seem to care.

We are now expected to put up with a caravan that could leak again for probably the next few months. 
How is it possible that Swift don’t have the replacement as they are fitting them to their new caravans. Needless to say we are very dissatisfied and disappointed. 

Has anyone had this problem and how was it resolved?