A Business Letter.

The article below I write is a reply to a letter of complaint. This is my first time to write such a formal letter, so I would need your help to tell me if this is eligible, which means if the way I talk in the letter is formal enough and whether the reason I give in the letter is acceptable or not. Oh, and please also correct the grammar mistakes. ._. Thank you all in advance! :)


Dear Sir,

In response to your letter of complaint regarding the temporary administrative assistant our company sent you, I would like to apologize.

Due to the fact that administrative assistants are in high demand, our experienced staff was fully occupied before you asked for one. We decided to give you a newly recruited employee, still under the training, to fulfill this vacancy. We apologize for our lack of careful handling and will avoid this situation in the future.

We would be very grateful if you gave us a second chance.  During your next visit, we will send you a temporary assistant, free of charge. We hope you accept this compensation and continue business with us in the future.

With apologies once again,

XXX

A Business Letter.

The article below that I have written is a reply to a letter of complaint. This is my first time to writing such a formal letter, so I would need your help to tell me if this is eligible, which means if the way I talk in the letter is formal enough and whether the reason I give in the letter is acceptable or not. Oh, and please also correct the grammar mistakes. ._. Thank you all in advance! :)


Dear Sir,
In response to your letter of complaint about regarding the temporary administrative assistant our company sent you who didn’t meet your satisfaction, I would like to apologize. I am writing this letter to explain to you how this all happened occurred.

Here is the reason why this unhappy thing happened. You may not know, that our employees are sorted into different groups according to the various needs of our costumers. All of the employees have to been trained at the same time when they join our company. We keep expanding the amount of our employees our workforce to meet the growing demand in the market. Unfortunately, due to the fact that administrative assistants are in badly need high demand these days, the our experienced old staff had all been occupied before you asked for requested one. After we thought repeatedly a quick thought, we decided to give the newly-recruited employee, who is still under the training, this opportunity. We must apologize for taking it lightly our lack of careful handling.

Our company has been in operation for 3 years already and has a very good reputation for sending satisfactory temporary workers quick with accuracy promptly and effectively. I believe that's is the reason why you chose ask us, and allow me to show my great thankfulness for your trusting us. I beg your understanding and forgiveness since this is the first time that this kind of case happens situation has happened and I can promise that this would will never happen again.

We would be very appreciative if you could give us a second chance by taking receiving our compensation. We will send you a temporary assistant, free of charge, when you are in need once the next time. With apologies once again.

Yours faithfully, Sincerely, 
XXX