Explanation
Dear Mr. / Ms,
I was very concerned when I received your letter of yesterday complaining that the central heating system in your new house had not been completed by the date promised.
On referring to our earlier correspondence,I find that I had mistaken the date for completion. The fault is entirely mine and I deeply regret that it should have occurred.
I realize the inconvenience our oversight must be causing you and will do everything possible to avoid any further delay. I have already given instructions for the work to have priority and the engineers working on the job to be placed on overtime. These arrangements should see the installation completed by next weekend.
Yours faithfully
解釋
尊敬的先生/小姐，
昨天收到你的來信，抱怨你新家的中央加熱系統未按規定時間裝好，對此我非常關心。參考較早的通信，我發現我搞錯了完成日期。錯誤完全是我的，對此我非常抱歉。
認識到我們的'疏忽給你造成的不便，我們將竭盡全力避免再耽擱。我已指示這項工作優先做並讓工程人員加班。這樣安排會於下週完成安裝。
你誠摯的