I need to send a formal letter to [client_name] regarding the renewal of their service contract. Could you provide a draft for this letter? The letter should be professional and polite, and should remind [client_name] about the upcoming renewal date [renewal_date]. Also, mention that we are offering a [discount_percentage]% discount on the renewal to show our appreciation for their continued business. The letter must contain at least 3 placeholders represented by square brackets, such as [address]. Highlight at least 2 sections in your answer with markdown, i.e. *highlighted section*.
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