Aslı

Short, honest, no blame, and a clear statement that it has stopped. That is the whole template.

It is absolutely worth asking, it works more often than people expect for individuals, and the message is short. I have had two waived.

What goes in it:

Own it immediately. One sentence: I misconfigured X and it ran from the second to the eleventh. Do not construct a story about ambiguous documentation. Support have seen every version of that and honesty is genuinely the thing that gets these approved.

Say what you have already fixed. The resource is deleted, here is the graph showing the charges stopped, I have added a budget alert at this threshold. This is the most important part, you are showing you are not going to be back next month.

Say what you were expecting to spend. A hobby project on a small budget is a different conversation from a company. Give the real number.

Make a specific, reasonable ask. A one-time waiver as a courtesy, or a partial. Asking for everything is fine; demanding is not.

Keep it under two hundred words.

What not to do: threaten to leave, mention that you will post about it publicly, or argue that the pricing is unfair. All three move you from a courtesy request to an argument you cannot win.

Expect a partial as often as a full waiver, and be pleased with either.