Define the issue in one sentence
Say which bill, reading, payment or balance you are querying and what you want the supplier to explain or correct. A narrow question is easier to answer than a general statement that the account is wrong.
Attach only useful evidence
Keep the relevant dates, readings, reading types, rates and payment history. Share account references only through the supplier’s normal secure channel and avoid sending unrelated personal or financial information.
Ask for a response you can check
Request the calculation, the readings used and the account balance treatment. If you want a correction, identify the figure and the evidence that supports reviewing it.
Keep a simple chronology
Record when you contacted the supplier, what it said and what remains unanswered. If the first response misses the question, restate the missing point and keep the original reference rather than starting again.