So we have a happy ending, or an ending where I got what I wanted because I stamped my feet and shouted loud enough!
Swiftcover refused to authorise the repair to the car through both Autoglass and National even though we are fully covered and I made sure to follow all procedures (logging calls etc...) saying that the cost of repair was outside of approved limits even though there's nothing in the policy booklet about it!
I eventually spoke to someone who was half decent and they told me that because the claim is so close to the renewal and it is an expensive windscreen that they would delay delay delay until the policy lapsed. They would then simply refuse to pay out even though the original claim to do the windscreen was put in when the policy was live essentially pushing the claim to a new insurer and that there was nothing that she could do.
They got so fed up with me they said that they would only talk to the policyholder which is my wife as it's technically her car, bad move on their part!!
So she just logged a formal complaint, giving all of the call details etc...
About 24 hours later I was called by someone and they told me that as long as I used Autoglass that they would approve the claim. So I thought sod it, I'll try them again, requested a dealer screen rain sensor etc...
Before booking we were careful to ensure that my wife got her proof of no claims printed off before they tried any funny business.
Spoke to someone at Autoglass who had a brain and got everything ordered and booked in, the chap came out on Sunday to do it. I have to say I was very surprised. This guy was extremely professional (he did have a black eye though!!), the correct screen was in the van, didn't need a rain sensor in the end because I have the type that clips to the screen rather than being bonded to it (he explained that some do and some don't).
So now I have a new screen, it doesn't leak and everything works. The DAB radio now gets a better reception strangely!
And we have changed our insurers!
Just need some new wiper blades now.