Please make sure that this will not happen again. It happened twice in the past. And every time it caused a downtime of 2 to 3 hours. My customers are very displeased. I require this issue to be addressed seriously and appropriately. And I don't want this to happen a third time. I reserve the right to take further actions.
以上翻译非常正式,措辞比较严肃但是有礼。
Please make sure that this will not happen again. It happened twice in the past. And every time it caused a downtime of 2 to 3 hours. My customers are very displeased. I hope you can address this issue appropriately. And hopefully it won't happen a third time.