Dear Ms. Helen,
Thank you for sending us the goods on Special Offer (Invoice No. 12345). We are honored to be one of your valued customers.
We are able to accept some of the goods you sent, but there are some that we are already overstocked with. So we have to return them to you. We enclose, with this letter, a copy of our d/o of the goods we are returning. Please send us a c/n for the goods returned.