amazon polly使用字數異常增加(The characters increased for no reason)

I'm using amazon polly in free-tier. The usage value of characters increased for no reason. According to the report the system created, even when i didn't use amazon polly, the usage value still increased. The most weird thing is that I registered my account this year, but the report shows I used the service in 2007. I want to know what's wrong with the usage value. Did I do anything wrong? How to solve the problem?

amazon polly顯示的字數用量與我實際使用情形不符，根據下載用量報告顯示的數據，在我未使用polly服務時，仍有用量增加的情形，甚至我的帳號是今年才註冊，但使用數據卻連2007年都有。依照我的使用情形，我的實際用量應該沒有系統計算的這麼多(我目前對用量計算的理解是文字生成為可下載的音訊檔才會被計入使用額度)，想知道是甚麼原因造成異常的數據，以及是否有解決方式。