Dear Mr. / Ms

尊敬的先生/小姐,

We are much concerned that your sales in recent months have fallen considerably.
我们非常关心你方销售近几个月大幅度下降。

At first we thought this might be due to a slack market, but on looking into the matter more closely,
开始我们以为是市场疲软,但仔细研究问题,

we find that the general trend of trade during this period has been upwards.
我们发现过去这段时间贸易的总趋势是上升的。

It is possible that you are facing difficulties of which we are not aware.
有可能你方面临我方还不知道的困难,

If so, we would like to know what we can do to help.
如是这样,我方想知道是否能帮助什么。

We, therefore, look forward to receiving from you a detailed report on the situation 
我们期望收到关于问题的详细报告,

and suggestions as to how we may help in restoring our sales to their former level.
及建议我们怎样帮助才能把销售恢复到原来的水平。