There are no NEOs on line right now but a few (about half a dozen I think) came with the new cabin but I don't think the older fleet have been retrofitted get. I think it's G-EZPM onwards.
I can't think why they would need to change any assignments on the seats. As far as I've seen there's been two half rows added on the right side of the cabin. The rest of the cabin remains unchanged.
I can't think why any currently booked seats would have to be switched so I'm inclined to think it's been switched to an A319.