ترجمة - إسبانيّ -انجليزي - No he podido mandarte el mp3 defectuoso...

I have not been able to mail COD the defective MP3 because it is not possible between Spain and Ireland. I have to pay 3 euros again to send it to you (in total, I will have paid 6 euros in shipping). If I mail it back anyway, can you assure me that you will mail an MP3 in good working condition?