IIRC we paid 100% of our bills during the dispute period -- after subtracting the mistake over-spend.

In the end we got 100% credit (forgiveness)

You ultimately need to sell the vision to GCP that you are worth more to them alive than dead.

I would include in your pitch the 37 specific measures you have taken so this doesn't happen again. And if another service goes wild you will catch it within an hour or two.