Dear Name,
We are really sorry for the inconvenience you had with the defective model of the computer. We received a letter stating that you would like a different model. We will definitely replace the computer for you if you can please send the computer with the original bill and we will transport the model you requested. We assure you that this would be a model you like and you will not face any problem. Last model was from the lot which was missed out from the stages of testing. It happens very rarely but we apologize for our mistake and assure you that we will be providing you with the mew model as soon as possible.