我想写信告诉你，我们对你的服务非常失望。 我们已经预订了一张桌子，但是当我们按预定的时间去那里的时候，却被告知没有座位了。

I am writing to tell you that we were quite disappointed with your service. We had booked a table, but when we went there at the time as arranged, only to be told there were no seats available.

youdao

会议将按预定的计划进行。

The meeting will take place [proceed] as planned.

《新英汉大辞典》

如果一切按预定的计划进行，我们两个星期后来。

If everything goes according to schedule, we will be back in two weeks.

youdao