Managed to get the connector off eventually and all the pins reset as they should be by a friendly professional.
Here's a before, an after and how it should look when it's all back together again. I also added a couple of matching coloured tie wraps to ensure it doesn't happen again.
But to get the seats out is a doddle and while I was there I took Matts advice to hoover and shampoo the carpets. The seat also got a clean and feed while it was out.