Write to feedback. They can be slow to respond, but I have had good results with them in the past. It may take up to two weeks, but ranting and railing against it isn't going to help.

Remember to be as calm and collected as you can be when you write them. Explain the situation in as much detail as you can, including specific messages and why you chose to ignore them. There is no guraantee that they will overturn the Warning, but if you are reasonable and do not have an extensive history of problems it is likley that they will be able to help you.

Remember: calm, patient, polite, and specific.