zest不给我退票

各位大侠，请问一下，我家里有事情，去菲律宾的计划要搁浅了。 我是4月份定的是zest的8月14日到8月18日上海往返马尼拉的飞机票。正好8月18日是周六，zest把马尼拉回上海的航班时间从20：10提前到了19：00，我以他们提前了起飞时间为由，要求退机票，可是他们最终认定不给退啊。请问我再发邮件要求退票还有用吗？如果他们不给我全额退票，我自己损失一点，可以退到多少？我上海来回马尼拉大概是900元左右的样子。

这个是zest给我的回复


Good day.


We would like to inform you that all the necessary documents presented to us in connection with your request to refund your ticket in full were thoroughly evaluated and assessed following the standard evaluation procedures. Much to our regret, the aforementioned request has been declined and is deemed final.


Thank you.