Voting is important, and unexpectedly high turnout can occur when there are major issues or the result seems close. This can be easily fixed, while retaining cut-offs. The main problem is attitude. Convenience of broadcasters should not be a factor.
All polling stations should stay open 1 hour later during General Elections – the current closing time dates from 2 generations ago when society closed earlier.
Allow optional extensions of no more than 1 hour if there are queues or other impediments to voting (like no ballot papers).
Always resource for 100% turnout. Penny pinching is stupid.
If an extension is required find away of identifying people who have turned up in time, but limit late voting to them. Perhaps "work the line" giving out tokens, or stamp the cards sent through the post.