Work out how to cut one painful bill roughly in half

Help me cut one painful bill as far as I reasonably can.

Which bill: [energy, broadband, mobile, car insurance, something else]
What I pay now: [amount and how often]
What I use it for: [details]
What I can't lose: [e.g. upload speed for work, a second car for school runs]
What I've already tried: [list]

Ask me up to 3 short questions first if anything important is missing. Wait for my answers.

Then:
1. Options that could cut it a lot, each with roughly how much it might save and the hassle.
2. How close each gets to half on my numbers, without inventing tariffs.
3. The first step for the best two options.
4. What to get in writing before I switch or change.

Mark guesses clearly. Only use what I've told you, leave blanks for anything I haven't given, and don't invent facts, figures or products. This is help organising my own numbers and wording, not financial advice; point me to MoneyHelper, GOV.UK or Citizens Advice for guidance, and to a free regulated debt adviser if I'm struggling to pay. UK English.

For current switching and comparison guidance on GOV.UK or MoneyHelper for this type of bill, use web search and name the page you used. If it doesn't search on its own, open View all tools and choose Search.

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