Contact Vendor Support. They will be able to see the message logs and they will see that you did send the links and they will be able to do something about it (I think). But, I would recommend messaging the buyer about the rating and explain that you did send a message to him with the download link. Always be professional when dealing with customers because this will help them realize that you are doing your best and they know that you deserve a good rating. I had this problem once with my free raffle, someone left me a 1 of 5 for something that I offer for free! I sent them a nice message asking what they were unhappy about and what I could do for them to change my rating to a 5 - they changed the rating almost immediately and replied to me apologizing.Hope this was helpful.Best regards,The Godfather