People keep mentioning a one-pager. What exactly do you include?
What to put in a one-page summary?
Account info + error description + dates + tariff cite + refund estimate + your contact.
I add screenshots of the bill line items. Makes it hard for them to misread.
Keep it neutral: observed discrepancy not utility overbilled us.
And always attach the LOA and at least 2 sample bills showing the pattern.
I also put a requested action line: re-rate, rebill months, confirm forward billing.