Dear Sir or Madam,
Thank you for letter of 5 May 20xx.
I must apologies for the delay in replying to your letter of 15 April. Unfortunately some members of our staff have recently been off sick. This, at a time when several of our employees take their annual leave, has resulted in unavoidable delays in replying to letters.
I enclose the price list of our company as requested and look forward to hearing from you.
Your sincerely
