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.

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。